Solid electrolyte separator bonding agent

ABSTRACT

Set forth herein are electrochemical cells which include a negative electrode current collector, a lithium metal negative electrode, an oxide electrolyte membrane, a bonding agent layer, a positive electrode, and a positive electrode current collector. The bonding agent layer advantageously lowers the interfacial impedance of the oxide electrolyte at least at the positive electrode interface and also optionally acts as an adhesive between the solid electrolyte separator and the positive electrode interface. Also set forth herein are methods of making these bonding agent layers including, but not limited to, methods of preparing and depositing precursor solutions which form these bonding agent layers. Set forth herein, additionally, are methods of using these electrochemical cells.

This application claims priority to, and the benefit of, U.S.Provisional Patent Application No. 62/336,474, filed, May 13, 2016,entitled SOLID ELECTROLYTE SEPARATOR BONDING AGENT, and U.S. ProvisionalPatent Application No. 62/448,294, filed Jan. 19, 2017, entitled SOLIDELECTROLYTE SEPARATOR BONDING AGENT, the entire contents of each ofwhich are herein incorporated by reference in their entirety for allpurposes.

BACKGROUND

In a rechargeable Li⁺ ion battery, Li⁺ ions move from a negativeelectrode to a positive electrode during discharge and in the oppositedirection during charge. This process produces electrical energy(Energy=Voltage×Current) in a circuit connecting the electrodes, whichis electrically insulated from, but parallel to, the Li⁺ ion conductionpath. The battery's voltage (V versus Li) is a function of the chemicalpotential difference for Li situated in the positive electrode ascompared to the negative electrode and is maximized when Li metal isused as the negative electrode. An electrolyte physically separates andelectrically insulates the positive and negative electrodes while alsoproviding a conduction medium for Li⁺ ions. The electrolyte ensures thatwhen Li metal oxidizes, at the negative electrode during discharge(e.g., Li↔Li⁺+e⁻), and produces electrons, these electrons conductbetween the electrodes by way of an external circuit which is not thesame pathway taken by the Li⁺ ions.

Conventional rechargeable batteries use liquid electrolytes to separatethe positive and negative electrodes. However, liquid electrolytessuffer from several problems including flammability during thermalrunaway, outgassing at high voltages, and chemical incompatibility withlithium metal negative electrodes. As an alternative, solid electrolyteshave been proposed for next generation rechargeable batteries. Forexample, Li⁺ ion-conducting ceramic oxides, such as lithium-stuffedgarnets, have been considered as electrolyte separators. See, forexample, US Patent Application Publication No. 2015/0099190, publishedApr. 9, 2015, and filed Oct. 7, 2014, titled GARNET MATERIALS FOR LISECONDARY BATTERIES AND METHODS OF MAKING AND USING GARNET MATERIALS;U.S. Pat. Nos. 8,658,317; 8,092,941; and 7,901,658; also U.S. PatentApplication Publication Nos. 2013/0085055; 2011/0281175; 2014/0093785;and 2014/0170504; also Bonderer, et al. “Free-Standing Ultrathin CeramicFoils,” Journal of the American Ceramic Society, 2010, 93(11):3624-3631;and Murugan, et al., Angew Chem. Int. Ed. 2007, 46, 7778-7781), theentire contents of each of these publications are incorporated byreference in their entirety for all purposes.

Solid electrolytes should reduce a battery's total weight and volumewhen paired with a lithium metal anode, when compared to a liquidelectrolyte paired with a graphite anode, and thereby should increaseits gravimetric and volumetric energy density. Despite these advantages,solid electrolytes are still insufficient in several regards forcommercial applications. For example, when a battery with a lithiummetal negative electrode charges and discharges, it expands andcontracts as the lithium conducts between the electrodes. This expansionand contraction can lead to delamination of a solid electrolyteseparator, positioned between a positive and negative electrode, fromeither or both of the positive and negative electrodes. Moreover, evenin the absence of delamination, solid interfaces tend not to perfectlyalign with each other. If a solid lithium metal negative electrode islaminated to a solid electrolyte, and the solid electrolyte (i.e.,separator), on the opposing side, is laminated to a positive electrode,each solid interface (Li-separator & Separator-Cathode) may haveinsufficient electrical contact due to areas where one solid interfacedoes not perfectly align and contact another solid interface. When solidelectrolytes are used to separate solid positive and negativeelectrodes, gaps or areas of non-contact may build up between the solidinterfaces, e.g., the interface of the electrolyte and the positiveelectrode. Areas of non-contact between the solid electrolyte and thepositive electrode result in impedance rises which reduce a battery'spower and capacity. To date and the best of Applicant's knowledge, thereare no public disclosures of commercially viable solid electrolyteseparators which interface with a solid positive electrode with asufficiently low interfacial resistance suitable for a commercialapplication.

When, for example, a solid separator such as a lithium-stuffed garnetelectrolyte monolith contacts a positive electrode, there may beinterfacial impedance between the solid electrolyte and the positiveelectrode due to poor wetting of the positive electrode, or itscatholyte, onto the solid electrolyte surface, low ion-conductivity ineither the separator or the electrode, or chemical reactions between thepositive electrode and the solid electrolyte which produce side productsdetrimental to electrochemical performance. To address some of thesechallenges, certain researchers have attempted to combine liquid and gelelectrolytes with lithium-stuffed garnets. See, for example, K. Yoshima,et al., Journal of Power Sources, 302 (2016) 283-290. However, noreported methods to date address these challenges for a battery thatuses a lithium metal negative electrode. For example, while someresearchers combined liquid electrolytes with lithium-stuffed garnets,the electrolytes used were insufficiently dense or of the incorrect formfactor to protect a lithium metal negative electrode from exposure tothe volatile components of the electrolyte. Also, for example, theseelectrolytes were insufficiently dense or of the incorrect form factorto protect an electrochemical cell from lithium dendrite growth. Assuch, the components in the liquid electrolyte would not be separatedfrom a lithium metal negative electrode if one were used with theseprior methods.

There is therefore a need for improved materials and methods for bondingelectrolyte separators to positive electrodes. What is needed are, forexample, new bonding agents for bonding a solid separator, e.g., alithium-stuffed garnet separator, to a positive electrode in such a waythat the bonding agent, the electrolyte or the catholyte in the positiveelectrode, do not detrimentally react with the Li metal in a lithiummetal negative electrode but still provide a conduction medium for Li⁺ions to conduct between the electrodes. What is also needed in therelevant field is a material which bonds or adheres, or maintains directcontact between, a solid separator and a positive electrode and alsolowers the resistance/impedance at the interface therebetween. Theinstant disclosure sets forth such materials and methods, in addition tomaking and using such materials and methods, and other solutions toproblems in the relevant field.

BRIEF SUMMARY

In one embodiment, the instant disclosure sets forth an electrochemicalstack which includes a lithium metal (Li) negative electrode, a positiveelectrode, an electrolyte separator in direct contact with the Li metalnegative electrode, and a bonding layer comprising a lithium salt, apolymer, and a solvent. In some examples, the bonding layer is a gelelectrolyte. The bonding layer directly contacts, and is positionedbetween, the electrolyte separator and the positive electrode, and theelectrolyte separator protects the Li metal negative electrode fromexposure to the polymer or to the solvent, or both, in the bondinglayer. As described herein, in some examples, the bonding layer lowersthe interfacial impedance at the interface between the electrolyteseparator and the positive electrode when compared to the electrolyteseparator in direct physical contact with the positive electrode. Insome examples, the bonding layer lowers the interfacial impedance at theinterface between the electrolyte membrane and the positive electrode bya factor of at least 10, at least 100, or at least 1000 with respect tothe interfacial impedance at the interface between the electrolytemembrane and the positive electrode when a bonding layer is notpositioned between, the electrolyte membrane and the positive electrode.

In a second embodiment, the instant disclosure sets forth a method ofmaking a free standing gel electrolyte, wherein the method includes spincoating solution to form a gel electrolyte onto a solid separator,wherein the solution includes two or more solvents, wherein the two ormore solvents have different boiling points, and volatilizing at leastone of the two or more solvents to form a porous gel electrolyte on asolid separator.

In a third embodiment, the instant disclosure sets forth a method ofmaking an electrochemical stack having a solid electrolyte separator anda gel electrolyte.

In a fourth embodiment, the instant disclosure sets forth a method ofusing an electrochemical stack having a solid electrolyte separator anda gel electrolyte.

In a fifth embodiment, the instant disclosure sets forth aphase-inversion gel electrolyte on the surface of a solid separator incontact with a cathode, wherein the gel electrolyte can be cast, bonded,laminated or adhered to a solid separator through spin coating, doctorblading, or other related techniques.

In a sixth embodiment, the instant disclosure sets forth a method ofmaking a phase-inversion gel electrolyte.

In a seventh embodiment, the instant disclosure sets forth a method ofmaking an electrochemical stack having a solid electrolyte separator anda phase-inversion. In some examples, the phase inversion gel isspin-coated on the solid electrolyte separator.

In an eighth embodiment, the instant disclosure sets forth a method ofusing an electrochemical stack having a solid separator and aphase-inversion gel spin-coated on the electrochemical stack.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of an example electrochemical stack, 100, withcomparison to another example electrochemical stack, 101.

FIG. 2 shows the electrochemical performance of an electrochemical stackas set forth in the electrochemical stack, 100, with comparison to anelectrochemical stack as set forth in the electrochemical stack, 101.FIG. 2 is a plot of Voltage [V] as a function of Run time [s].

FIG. 3 shows a charge-discharge Galvanostatic Intermittent TitrationTechnique (GITT) plot for an electrochemical stack as set forth in theelectrochemical stack, 101. FIG. 3 is a plot of Voltage [V] as afunction of Cycle active mass-specific capacity [mAh/g].

FIG. 4 shows a scanning electron microscopy cross-sectional image of athin (˜0.3 μm) PVDF containing gel electrolyte, 401, on a glass slide,402. Scale bar is 5 μm.

FIG. 5 shows a scanning electron microscopy cross-sectional image of a47.4% polyacrylonitrile (PAN) gel electrolyte spin-cast onto a garnetseparator wherein the PAN gel is spin-cast at 2000 RPM. Scale bar is 100μm.

FIG. 6 shows a side view of an example electrochemical test step-up.

FIG. 7 shows a side view of an example electrochemical test step-up fordetermining the Area Specific Resistance (ASR) of the gel bonding layerwith the garnet electrolyte.

FIG. 8 shows a summary of interfacial ASR for various gel electrolytesas a function of the spin-casting RPM used to prepare the gelelectrolyte in an electrochemical cell and as set forth in theelectrochemical test step-up in FIG. 7 .

FIG. 9 shows a plot of interfacial impedance (Ω·cm²) as a function oftype of electrolyte material (liquid, gel, polymer, and solid) at 45° C.

FIG. 10 shows a plain view of the phase inversion spin-coated gel,showing porous morphology on a cross-sectional thickness of one micron.The scale bar is 10 μm.

FIG. 11 shows a cross-section (left-side scanning electron microscopeimages (SEM) of the phase inversion spin-coated gel, showing porousmorphology on a cross-sectional thickness of one micron. The scale baris 5 μm.

FIG. 12 shows a focused ion beam (FIB) scanning electron microscopycross-sectional image of a full cell cross section with a cathode incontact with PVDF-HFP phase inversion spin coated gel electrolyte onto agarnet separator where in the gel is spin-coated at 1200 RPM. Scale baris 10 μm.

FIG. 13 shows Electrochemical Impedance Spectrum (EIS) of thephase-inversion spin coated gel sandwiched between two oxide separatorpellets in a symmetric cell.

FIG. 14 shows the results of a contact angle measurement from Example 5.

The figures depict various embodiments of the present disclosure forpurposes of illustration only. One skilled in the art will readilyrecognize from the following discussion that alternative embodiments ofthe structures and methods illustrated herein may be employed withoutdeparting from the principles described herein.

DETAILED DESCRIPTION

The following description is presented to enable one of ordinary skillin the art to make and use the invention and to incorporate it in thecontext of particular applications. Various modifications, as well as avariety of uses in different applications will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to a wide range of embodiments. Thus, the inventions hereinare not intended to be limited to the embodiments presented, but are tobe accorded their widest scope consistent with the principles and novelfeatures disclosed herein.

All the features disclosed in this specification, (including anyaccompanying claims, abstract, and drawings) may be replaced byalternative features serving the same, equivalent or similar purpose,unless expressly stated otherwise. Thus, unless expressly statedotherwise, each feature disclosed is one example only of a genericseries of equivalent or similar features.

Please note, if used, the labels left, right, front, back, top, bottom,forward, reverse, clockwise and counter clockwise have been used forconvenience purposes only and are not intended to imply any particularfixed direction. Instead, they are used to reflect relative locationsand/or directions between various portions of an object.

GENERAL DESCRIPTION I. Introduction

Set forth herein are electrochemical cells which include a negativeelectrode current collector, a lithium metal negative electrode, a solidelectrolyte membrane (e.g., an electrolyte separator comprising alithium-stuffed garnet oxide), a bonding agent layer, a positiveelectrode, and a positive electrode current collector. As used herein, amembrane is a type of separator. In these cells, the lithium metalnegative electrode directly contacts and is positioned between thenegative electrode current collector and the electrolyte membrane; theelectrolyte directly contacts and is positioned between the lithiummetal negative electrode and the bonding agent layer; the bonding agentlayer directly contacts and is positioned between the electrolyte andthe positive electrode; and the positive electrode directly contacts andis positioned between the bonding agent layer and the positive electrodecurrent collector. The bonding agent layer advantageously lowers theinterfacial impedance of the oxide-based electrolyte at the positiveelectrode interface and also assists in the adhesion of the electrolyteto a positive electrode interface. The bonding layer, in some examples,is stable at high voltages (e.g., stable against chemical reaction above4.0 V, 4.1 V, 4.2 V, 4.3 V, 4.4 V, 4.5 V, or 4.6 V). Also set forthherein are electrochemical cell configurations wherein the bonding layeris physically separated from the lithium metal negative electrode by anoxide such as, but not limited to, a lithium-stuffed garnet, a lithiumaluminum titanium phosphate, or a lithium germanium titanium phosphate.In some examples, these oxides are sintered, dense, pinhole,defect-free, or combinations thereof such that neither the solvent norpolymer included in the bonding agent layer directly contacts thelithium metal negative electrode. Also set forth herein are methods ofmaking these bonding agent layers including, but not limited to, methodsof preparing and depositing precursor solutions which form these bondingagent layers. Set forth herein, additionally, are methods of using theseelectrochemical cells. Also, set forth herein are free standing layersof a gel electrolyte which can be included in an electrochemical deviceor stack described herein as a bonding layer. Also, set forth, herein,is a phase-inversion gel electrolyte which is spin-coated, or otherwisecoated to, laminated on, or in contact with the surface of the solidseparator which can be included in an electrochemical device or stack.

II. Definitions

As used herein, the term “about,” when qualifying a number, e.g., 15%w/w, refers to the number qualified and optionally the numbers includedin a range about that qualified number that includes ±10% of the number.For example, about 15% w/w includes 15% w/w as well as 13.5% w/w, 14%w/w, 14.5% w/w, 15.5% w/w, 16% w/w, or 16.5% w/w. For example, “about75° C.,” includes 75° C. as well 68° C., 69° C., 70° C., 71° C., 72° C.,73° C., 74° C., 75° C., 76° C., 77° C., 78° C., 79° C., 80° C., 81° C.,82° C., or 83° C.

As used herein, the term, “Ra,” is a measure of surface roughnesswherein Ra is an arithmetic average of absolute values of sampledsurface roughness amplitudes. Surface roughness measurements can beaccomplished using, for example, a Keyence VK-X100 instrument thatmeasures surface roughness using a laser. As used herein, the term,“Rt,” is a measure of surface roughness wherein Rt is the maximum peakheight of sampled surface roughness amplitudes. Disclosed herein aremethods of modifying the surface roughness of an electrolyte, whichmethods include polishing, ablating, exposing to laser, exposing toplasma, exposing to ozone, exposing to a reducing atmosphere at elevatetemperatures such as but not limited to 400° C., 500° C., 600° C., 700°C., 800° C., 900° C., 1000° C., 1100° C., 1200° C., 1300° C., or higher,or annealing the surface in order to achieve the desired surfaceroughness.

As used herein, “selected from the group consisting of” refers to asingle member from the group, more than one member from the group, or acombination of members from the group. A member selected from the groupconsisting of A, B, and C includes, for example, A only, B only, or Conly, as well as A and B, A and C, B and C, as well as A, B, and C.

As used herein, the phrases “electrochemical cell” or “battery cell”shall mean a single cell including a positive electrode and a negativeelectrode, which have ionic communication between the two using anelectrolyte. In some embodiments, the same battery cell includesmultiple positive electrodes and/or multiple negative electrodesenclosed in one container.

As used herein the phrase “electrochemical stack,” refers to one or moreunits which each include at least a negative electrode (e.g., Li, LiC₆),a positive electrode (e.g., Li-nickel-manganese-oxide or FeF₃,optionally a gel electrolyte), and a solid electrolyte (e.g., anelectrolyte set forth herein). In some examples, between the solidelectrolyte and the positive electrode, there is an additional layercomprising a gel electrolyte. An electrochemical stack may include oneof these aforementioned units. An electrochemical stack may includeseveral of these aforementioned units arranged in electricalcommunication (e.g., serial or parallel electrical connection). In someexamples, when the electrochemical stack includes several units, theunits are layered or laminated together in a column. In some examples,when the electrochemical stack includes several units, the units arelayered or laminated together in an array. In some examples, when theelectrochemical stack includes several units, the stacks are arrangedsuch that one negative electrode is shared with two or more positiveelectrodes. Alternatively, in some examples, when the electrochemicalstack includes several units, the stacks are arranged such that onepositive electrode is shared with two or more negative electrodes.Unless specified otherwise, an electrochemical stack includes onepositive electrolyte between the positive electrode and the solidelectrolyte.

As used herein, the phrases “gel electrolyte,” unless specifiedotherwise, refers to a suitable Li⁺ ion conducting gel or liquid-basedelectrolyte, for example, those set forth in U.S. Pat. No. 5,296,318,entitled RECHARGEABLE LITHIUM INTERCALATION BATTERY WITH HYBRIDPOLYMERIC ELECTROLYTE, which is incorporated by reference in itsentirety for all purposes. A gel electrolyte has lithium ionconductivity of greater than 10⁻⁵ S/cm at room temperature, a lithiumtransference number between 0.05-0.95, and a storage modulus greaterthan the loss modulus at some temperature. A gel may comprise a polymermatrix, a solvent that gels the polymer, and a lithium containing saltthat is at least partly dissociated into Li⁺ ions and anions. Herein, insome examples, the gel electrolyte is used as the bonding layer.

As used herein, the phrase “one stage gel electrolyte,” refers to anelectrolyte made using a single precursor solution which alreadyincludes an electrolyte solution and lithium salt and which is cast andallowed to evaporate the higher boiling point solvents.

As used herein, the phrase “two stage gel electrolyte,” refers to anelectrolyte made using a precursor solution which includes a polymer anda plasticizer. After casting this solution, in a first stage, theplasticizer is either leached out, using a solvent in second stage, ordried; the resulting porosity is refilled by soaking it in anelectrolyte solution.

As used herein, the phrase “phase-inversion gel electrolyte”, unlessspecified otherwise, refers to a suitable Li⁺ ion conducting gel formedby a controlled polymer transformation from a liquid phase to solidphase. The phase inversion gel electrolyte includes a polymer with asolvent, and a second solvent which does not solvate the polymer, and alithium salt, wherein the concentration of the polymer is 2-10% byvolume, wherein the concentration of the lithium salt is 8-12% byvolume, and where the composition includes at least 20-40% by porosityby volume. To make a phase-inversion gel electrolyte, the polymer inthis case is dissolved in a solvent and non-solvent mixture. A lithiumsalt is then added. The evaporation of the solvent due to highvolatility occurs or is induced, causing the composition to have ahigher non-solvent concentration in the mixture. The polymerprecipitates and forms a porous membrane, resulting in a phase-inversiongel electrolyte which includes the lithium salt.

As used herein, the phrase “spin-coated” or “spin-casted” refers to aprocess used to deposit a uniform thin film on a substrate. This can beaccomplished by applying a small amount of viscous coating material tothe substrate. The substrate is rotated during or after the applicationof the coating material to form a relatively uniform coating thickness.

As used herein, the phrase “non-solvent” refers to a liquid in which thepolymer has little to no solubility. In some examples, the non-solventis toluene when the polymer is PVDF-HFP. In other examples, thenon-solvent is dibutyl phthalate (DBP), glycerol, or carbonateelectrolyte solvents such as ethylene carbonate when the polymer isPVDF-HFP.

As used herein, the phrase “solvent” refers, unless specified otherwise,to a solvent which dissolves the polymer used in the gel electrolyte orphase inversion gel. In some examples, the solvent is tetrahydrofuranwhen the polymer is PVDF-HFP. In other examples, the solvent isdimethylformamide (DMF) or N-methyl-pyrrolidone (e.g.,N-methyl-2-pyrrolidone or NMP) when the polymer is PVDF-HFP.

As used herein, the terms “cathode” and “anode” refer to the electrodesof a battery. During a charge cycle in a Li-secondary battery, Li ionsleave the cathode and move through an electrolyte, to the anode. Duringa charge cycle, electrons leave the cathode and move through an externalcircuit to the anode. During a discharge cycle in a Li-secondarybattery, Li ions migrate towards the cathode through an electrolyte andfrom the anode. During a discharge cycle, electrons leave the anode andmove through an external circuit to the cathode. Unless otherwisespecified, the cathode refers to the positive electrode. Unlessotherwise specified, the anode refers to the negative electrode.

As used herein, the term “catholyte,” refers to a Li ion conductor thatis intimately mixed with, or that surrounds, or that contacts thepositive electrode active materials and provides an ionic pathway forLi⁺ to and from the active materials. Catholytes suitable with theembodiments described herein include, but are not limited to, catholyteshaving the common name Li-stuffed garnets, LPS, LXPS, LATS, or LXPSO,where X is Si, Ge, Sn, As, Al, or also combinations thereof, and thelike. Catholytes may also be liquid, gel, semi-liquid, semi-solid,polymer, and/or solid polymer ion conductors known in the art ordescribed herein. Catholytes include those catholytes set forth in USPatent Application Publication No. 2015-0171465, which published on Jun.18, 2015, entitled SOLID STATE CATHOLYTE OR ELECTROLYTE FOR BATTERYUSING Li_(A)MP_(B)S_(C) (M=Si, Ge, AND/OR Sn), filed May 15, 2014, andwhich is now U.S. Pat. No. 9,172,114, the contents of which areincorporated by reference in their entirety. Catholytes are also foundin U.S. Pat. Nos. 9,553,332 and 9,634,354, the contents of which areincorporated by reference in their entirety. Catholytes include thosecatholytes set forth in US Patent Application Publication No.2015/0099190, published on Apr. 9, 2015, entitled GARNET MATERIALS FORLI SECONDARY BATTERIES AND METHODS OF MAKING AND USING GARNET MATERIALS,and filed Oct. 7, 2014, the contents of which are incorporated byreference in their entirety. In some examples, the gel electrolyte(e.g.,) referred to herein is an 80:20 to 50:50 vol. % PVDF-HFP toEC:EMC. Herein, PVDF is polyvinylidene fluoride; HFP ishexafluorophosphate; EC is ethylene carbonate; and EMC is ethyl methylcarbonate.

As used herein, the term “electrolyte,” refers to a material that allowsions, e.g., Li⁺, to migrate therethrough but which does not allowelectrons to conduct therethrough. Electrolytes are useful forelectrically isolating the cathode and anodes of a rechargeable (i.e.,secondary) battery while allowing ions, e.g., Li⁺, to transmit throughthe electrolyte.

As used herein, the phrase “d₅₀ diameter” or “median diameter (d₅₀)”refers to the median size, in a distribution of sizes, measured bymicroscopy techniques or other particle size analysis techniques, suchas, but not limited to, scanning electron microscopy or dynamic lightscattering. D₅₀ describes a characteristic dimension of particles atwhich 50% of the particles are smaller than the recited size. As usedherein “diameter (d₉₀)” refers to the size, in a distribution of sizes,measured by microscopy techniques or other particle size analysistechniques, including, but not limited to, scanning electron microscopyor dynamic light scattering. D₉₀ includes the characteristic dimensionat which 90% of the particles are smaller than the recited size. As usedherein “diameter (d₁₀)” refers to the size, in a distribution of sizes,measured by microscopy techniques or other particle size analysistechniques, including, but not limited to, scanning electron microscopyor dynamic light scattering. D₁₀ includes the characteristic dimensionat which 10% of the particles are smaller than the recited size.

As used herein, the term “rational number” refers to any number whichcan be expressed as the quotient or fraction (e.g., p/q) of two integers(e.g., p and q), with the denominator (e.g., q) not equal to zero.Example rational numbers include, but are not limited to, 1, 1.1, 1.52,2, 2.5, 3, 3.12, and 7.

As used herein, the phrase “subscripts and molar coefficients in theempirical formulas are based on the quantities of raw materialsinitially batched to make the described examples” means the subscripts,(e.g., 7, 3, 2, 12 in Li₇La₃Zr₂O₁₂ and the coefficient 0.35 in0.35Al₂O₃) refer to the respective elemental ratios in the chemicalprecursors (e.g., LiOH, La₂O₃, ZrO₂, Al₂O₃) used to prepare a givenmaterial, (e.g., Li₇La₃Zr₂O₁₂.0.35Al₂O₃).

As used herein, a “thickness” by which is film is characterized refersto the distance, or median measured distance, between the top and bottomfaces of a film. As used herein, the top and bottom faces refer to thesides of the film having the largest surface area.

As used herein, the phrase “density as determined by geometricmeasurements,” refers to measurements of density obtained by physicalmass and volume measurements. Density is determined by the ratio ofmeasured mass to the measured volume. Customary techniques including theArchimedes method may be employed for such determinations. Unless statedotherwise, the density as determined by geometric measurements is theArchimedes method.

As used herein, the phrase “density as measured by the Archimedesmethod,” refers to a density inclusive of closed porosity but exclusiveof open porosity. The dimensions of a dry part are measured and thevolume is calculated and recorded as Va.; the mass of the dry part ismeasured and recorded as m_(d). Vacuum infiltration of the part with asolvent such as toluene or IPA is then conducted by, for example,pulling a vacuum on the parts for at least one hour to a pressure lessthan −20 inHg and then submerge the parts in solvent, infiltrate for atleast 30 minutes. Next, the vacuum is released, keeping parts submergedin solvent. Then, the surface liquid is wiped off of the part, andrecord the mass m_(w) of the part when wet. Finally, recording the massm_(s) of the part when submerged in the cup is performed. The Archimedesbulk density is calculated as m_(d)/(m_(w)−m_(s))ρ_(s), where ρ_(s) isthe solvent density, and the open porosity is(m_(w)−m_(d))/(m_(w)−m_(s)).

As used herein, the phrase “density as determined by scanning electronmicroscopy (SEM),” refers to the analysis of scanning electronmicroscopy (SEM) images. This analysis includes measuring the relativeamounts of the electrolyte separator which are porous or vacant withrespect to the electrolyte separator which is fully dense. The SEMimages useful for this analysis include those obtained by SEMcross-sectional analysis using focused ion beam (FIB) milling.

As used herein, the phrase “porosity as determined by SEM,” refers tomeasurement of density by using an image analysis software. First, auser or software assigns pixels and/or regions of an image as porosity.Second, the area fraction of those regions is summed. Finally, theporosity fraction determined by SEM is equal to the area fraction of theporous region of the image. Herein, porosity by volume is determined bySEM as set forth in this paragraph unless stated otherwise to thecontrary.

As used herein, the term “laminating” refers to the process ofsequentially depositing a layer of one precursor species, e.g., alithium precursor species, onto a deposition substrate and thensubsequently depositing an additional layer onto an already depositedlayer using a second precursor species, e.g., a transition metalprecursor species. This laminating process can be repeated to build upseveral layers of deposited vapor, liquid, or semi-solid phases. As usedherein, the term “laminating” also refers to the process whereby a layercomprising an electrode, e.g., positive electrode or cathode activematerial comprising layer, is contacted to a layer comprising anothermaterial, e.g., garnet electrolyte. The laminating process may include areaction or use of a binder which adheres of physically maintains directcontact between the layers which are laminated.

As used herein, the term “electrolyte,” refers to an ionicallyconductive and electrically insulating material. Electrolytes are usefulfor electrically insulating the positive and negative electrodes of asecondary battery while allowing for the conduction of ions, e.g., Li⁺,through the electrolyte. In some of the electrochemical devicesdescribed herein, the electrolyte includes a solid film, pellet, ormonolith of a Li⁺ conducting oxide, such as a lithium-stuffed garnet. Insome examples, the electrolyte further includes a gel electrolyte whichis laminated to or directly contacting the solid film, pellet, ormonolith.

As used herein, the phrase “antiperovskite” refers to the family ofmaterials with an antiperovskite crystal structure and the compositionLi_(a)O_(b)X_(c)H_(d)M_(e) where X is selected from Cl, Br, I, and F andmixtures thereof, and M is selected from Al, Ge, and Ga. In the formulaLi_(a)O_(b)X_(c)H_(d)M_(e), the subscripts are chosen such that 2<a<4,0.7<b<1.3, 0.7<c<1.3, 0≤d<1, 0≤e<1.

As used herein, the phrase “lithium stuffed garnet” refers to oxidesthat are characterized by a crystal structure related to a garnetcrystal structure. Electrolytes include those electrolytes set forth inUS Patent Application Publication No. 2015-0171465, which published onJun. 18, 2015, entitled SOLID STATE CATHOLYTE OR ELECTROLYTE FOR BATTERYUSING Li_(A)MP_(B)S_(C) (M=Si, Ge, AND/OR Sn), filed May 15, 2014, andwhich is now U.S. Pat. No. 9,172,114, the contents of which areincorporated by reference in their entirety. Electrolytes are also foundin U.S. Pat. Nos. 9,553,332 and 9,634,354, the contents of which areincorporated by reference in their entirety. Electrolytes include thoseelectrolytes set forth in US Patent Application Publication No.2015/0099190, published on Apr. 9, 2015, entitled GARNET MATERIALS FORLI SECONDARY BATTERIES AND METHODS OF MAKING AND USING GARNET MATERIALS,and filed Oct. 7, 2014, the contents of which are incorporated byreference in their entirety. This application describes Li-stuffedgarnet solid-state electrolytes used in solid-state lithium rechargeablebatteries. These Li-stuffed garnets generally having a compositionaccording to Li_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F), orLi_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2.3, 10<F<13, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb, or Ta,or Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein 5<a<8.5; 2<b<4;0<c≤2.5; 0≤d<2; 0≤e<2, and 10<f<13 and Me″ is a metal selected from Nb,Ta, V, W, Mo, or Sb and as otherwise described in U.S. PatentApplication Publication No. U.S. 2015/0099190. In some examples, A maybe about 6.0 or about 6.1 or about 6.2 or about 6.3 or about 6.4 orabout 6.5 or about 6.6 or about 6.7 or about 6.8 or about 6.9 or about7.0 or about 7.1 or about 7.2 or about 7.3 or about 7.4. In someexamples, B may be about 2.8 or about 2.9 or about 3.0 or about 3.1 orabout 3.2. In some examples, C may be about 0 or about 0.1 or about 0.2or about 0.3 or about 0.4 or about 0.5 or about 0.6 or about 0.7 orabout 0.8 or about 0.9 or about 1.0 or about 1.1 or about 1.2 or about1.3 or about 1.4 or about 1.5 or about 1.6 or about 1.7 or about 1.8 orabout 1.9 or about 2.0. In some examples D may be about 0 or about 0.1or about 0.2 or about 0.3 or about 0.4 or about 0.5 or about 0.6 orabout 0.7 or about 0.8 or about 0.9 or about 1.0 or about 1.1 or about1.2 or about 1.3 or about 1.4 or about 1.5 or about 1.6 or about 1.7 orabout 1.8 or about 1.9 or about 2.0. In some examples, E may be about1.4 or about 1.5 or about 1.6 or about 1.7 or about 1.8 or about 1.9 orabout 2.0 or about 2.1 or about 2.2. In some examples, F may be about11.0 or about 11.1 or about 11.2 or about 11.3 or about 11.4 or about11.5 or about 11.6 or about 11.7 or about 11.8 or about 11.9 or about12.0 or about 12.1 or about 12.2 or about 12.3 or about 12.4 or about12.5 or about 12.6 or about 12.7 or about 12.8 or about 12.9 or about13.0. Herein, the subscript values and coefficient values are selectedso the compound is charge neutral unless stated otherwise to thecontrary. As used herein, lithium-stuffed garnets, and garnets,generally, include, but are not limited to,Li_(7.0)La₃(Zr_(t1)+Nb_(t2)+Ta_(t3))O₁₂+0.35Al₂O₃; wherein (subscriptst1+t2+t3=subscript 2) so that the La:(Zr/Nb/Ta) ratio is 3:2. Also,garnets used herein include, but are not limited to,Li_(x)La₃Zr₂O_(F)+yAl₂O₃, wherein x ranges from 5.5 to 9; and y rangesfrom 0 to 1. In these examples, subscripts x, y, and F are selected sothat the garnet is charge neutral. In some examples x is 7 and y is 1.0.In some examples, x is 5 and y is 1.0. In some examples, x is 6 and y is1.0. In some examples, x is 8 and y is 1.0. In some examples, x is 9 andy is 1.0. In some examples x is 7 and y is 0.35. In some examples, x is5 and y is 0.35. In some examples, x is 6 and y is 0.35. In someexamples, x is 8 and y is 0.35. In some examples, x is 9 and y is 0.35.In some examples x is 7 and y is 0.7. In some examples, x is 5 and y is0.7. In some examples, x is 6 and y is 0.7. In some examples, x is 8 andy is 0.7. In some examples, x is 9 and y is 0.7. In some examples x is 7and y is 0.75. In some examples, x is 5 and y is 0.75. In some examples,x is 6 and y is 0.75. In some examples, x is 8 and y is 0.75. In someexamples, x is 9 and y is 0.75. In some examples x is 7 and y is 0.8. Insome examples, x is 5 and y is 0.8. In some examples, x is 6 and y is0.8. In some examples, x is 8 and y is 0.8. In some examples, x is 9 andy is 0.8. In some examples x is 7 and y is 0.5. In some examples, x is 5and y is 0.5. In some examples, x is 6 and y is 0.5. In some examples, xis 8 and y is 0.5. In some examples, x is 9 and y is 0.5. In someexamples x is 7 and y is 0.4. In some examples, x is 5 and y is 0.4. Insome examples, x is 6 and y is 0.4. In some examples, x is 8 and y is0.4. In some examples, x is 9 and y is 0.4. In some examples x is 7 andy is 0.3. In some examples, x is 5 and y is 0.3. In some examples, x is6 and y is 0.3. In some examples, x is 8 and y is 0.3. In some examples,x is 9 and y is 0.3. In some examples x is 7 and y is 0.22. In someexamples, x is 5 and y is 0.22. In some examples, x is 6 and y is 0.22.In some examples, x is 8 and y is 0.22. In some examples, x is 9 and yis 0.22. Also, garnets as used herein include, but are not limited to,Li_(x)La₃Zr₂O₁₂+yAl₂O₃. In one embodiment, the Li-stuffed garnet hereinhas a composition of Li₇Li₃Zr₂O₁₂. In another embodiment, the Li-stuffedgarnet herein has a composition of Li₇Li₃Zr₂O₁₂.Al₂O₃. In yet anotherembodiment, the Li-stuffed garnet herein has a composition ofLi₇Li₃Zr₂O₁₂.0.22Al₂O₃. In yet another embodiment, the Li-stuffed garnetherein has a composition of Li₇Li₃Zr₂O₁₂.0.35Al₂O₃. In certain otherembodiments, the Li-stuffed garnet herein has a composition ofLi₇Li₃Zr₂O₁₂.0.5Al₂O₃. In another embodiment, the Li-stuffed garnetherein has a composition of Li₇Li₃Zr₂O₁₂.0.75Al₂O₃.

As used herein, garnet does not include YAG-garnets (i.e., yttriumaluminum garnets, or, e.g., Y₃Al₅O₁₂). As used herein, garnet does notinclude silicate-based garnets such as pyrope, almandine, spessartine,grossular, hessonite, or cinnamon-stone, tsavorite, uvarovite andandradite and the solid solutions pyrope-almandine-spessarite anduvarovite-grossular-andradite. Garnets herein do not includenesosilicates having the general formula X₃Y₂(SiO₄)₃ wherein X is Ca,Mg, Fe, and, or, Mn; and Y is Al, Fe, and, or, Cr.

As used herein, the phrases “garnet precursor chemicals,” “chemicalprecursor to a garnet-type electrolyte,” “precursors to garnet” and“garnet precursor materials” refer to chemicals which react to form alithium stuffed garnet material described herein. These chemicalprecursors include, but are not limited to lithium hydroxide (e.g.,LiOH), lithium oxide (e.g., Li₂O), lithium carbonate (e.g., LiCO₃),zirconium oxide (e.g., ZrO₂), zirconium hydroxide, zirconium acetate,zirconium nitrate, zirconium acetylacetonate, zirconium nitratex-hydrate, lanthanum oxide (e.g., La₂O₃), lanthanum hydroxide (e.g.,La(OH)₃), lanthanum nitrate, lanthanum acetate, lanthanumacetylacetonate, aluminum oxide (e.g., Al₂O₃), aluminum hydroxide (e.g.,Al(OH)₃), aluminum (e.g., Al), aluminum nitrate (e.g., Al(NO₃)₃),aluminum nitrate nonahydrate, boehmite, gibbsite, corundum, aluminumoxyhydroxide, niobium oxide (e.g., Nb₂O₅), gallium oxide (Ga₂O₃), andtantalum oxide (e.g., Ta₂O₅). Other precursors to garnet materials,known in the relevant field to which the instant disclosure relates, maybe suitable for use with the methods set forth herein.

As used herein the phrase “garnet-type electrolyte,” refers to anelectrolyte that includes a lithium stuffed garnet material describedherein as the Li⁺ ion conductor.

As used herein, the phrase “doped with alumina” means that Al₂O₃ is usedto replace certain components of another material, e.g., a garnet. Alithium stuffed garnet that is doped with Al₂O₃ refers to garnet whereinaluminum (Al) substitutes for an element in the lithium stuffed garnetchemical formula, which may be, for example, Li or Zr.

As used herein, the phrase “reaction vessel” refers to a container orreceptacle into which precursor chemicals are placed in order to conducta chemical reaction to produce a product, e.g., a lithium stuffed garnetmaterial.

As used herein, the term “defect” refers to an imperfection or adeviation from a pristine structure such as, but not limited to, a pore,a crack, a separation, a chemical inhomogeneity, or a phase segregationof two or more materials in a solid material. A perfect crystal is anexample of a material that lacks defects. A nearly 100% denseelectrolyte that has a planar surface, with substantially no pitting,cracks, pores, or divots on the surface, is an example of an electrolytethat is substantially lacking defects. A surface of an electrolyte issubstantially lacking defects if the defect density is less than 1defect per 1 mm². An electrolyte's bulk is substantially lacking defectsif the defect density is less than 1 defect per 1 mm³.

As used herein the term “porous,” refers to a material that includespores, e.g., nanopores, mesopores, or micropores.

As used herein, “flatness” of a surface refers to the greatest normaldistance between the lowest point on a surface and a plane containingthe three highest points on the surface, or alternately, the greatestnormal distance between the highest point on a surface and a planecontaining the three lowest points on the surface. It may be measuredwith an AFM, a high precision optical microscope, or laserinterferometry height mapping of a surface.

As used herein the phrase “free standing thin film,” refers to a filmthat is not adhered or supported by an underlying substrate. In someexamples, free standing thin film is a film that is self-supporting,which can be mechanically manipulated or moved without need of substrateadhered or fixed thereto. A free standing thin film can be laminated orbonded to a current collector or electrode, but such a free standingthin film is only free standing when not supported by an underlyingsubstrate.

As used here, the phrase “inorganic solid state electrolyte,” refers toa material not including carbon which conducts ions (e.g., Li⁺) but doesnot conduct electrons. Example inorganic solid state electrolytesinclude oxide electrolytes and sulfide electrolytes, which are furtherdescribed in the instant disclosure.

As used here, the phrase “directly contacts,” refers to thejuxtaposition of two materials such that the two materials contact eachother sufficiently to conduct either an ion or electron current. As usedherein, direct contact may also refer to two materials in contact witheach other and which do not have any other different types of solid orliquid materials positioned between the two materials which are indirect contact.

As used here, the phrase “composite separator” or “compositeelectrolyte” refer to a composite of a polymer and a solid ionconductor. The solid ion conductor may include any of the ion conductorsmentioned herein. The polymer may be an epoxy, a rubber, or anycomposition mentioned in US Patent Application Publication No.2017-0005367 A1, entitled COMPOSITE ELECTROLYTES, which was filed asU.S. patent application Ser. No. 15/192,960, filed Jun. 24, 2016, on 16which is incorporated herein by reference in its entirety for allpurposes. Examples composite separators may be found in US PatentApplication Publication No. 2017-0005367 A1, entitled COMPOSITEELECTROLYTES, which was filed as U.S. patent application Ser. No.15/192,960, filed Jun. 24, 2016. In some examples, the electrolytesherein may include, or be layered with, or be laminated to, or contact asulfide electrolyte. As used here, the phrase “sulfide electrolyte,”includes, but is not limited to, electrolytes referred to herein asLATS, LSS, LTS, LXPS, or LXPSO, where X is Si, Ge, Sn, As, Al. In theseacronyms (LSS, LTS, LXPS, or LXPSO), S refers to the element S, Si, orcombinations thereof, and T refers to the element Sn. “Sulfideelectrolyte” may also include Li_(a)P_(b)S_(c)X_(d),Li_(a)B_(b)S_(c)X_(d), Li_(a)Sn_(b)S_(c)X_(d) or Li_(a)Si_(b)S_(c)X_(d)where X═F, Cl, Br, I, and 10%≤a≤50%, 10%≤b≤44%, 24%≤c≤70%, 0≤d≤18%.Sulfide electrolytes may contain less than 5% or less than 10% oxygen.

In some examples, the sulfide electrolyte layer is a material containingSi, Li, O, P, and S and is referred to herein as a SLOPS material. Insome examples, the electrolyte layer is a material containing Si, Li, O,P, and S and is referred to herein as a SLOPS/LSS material. As usedherein, LSS includes, unless otherwise specified, a 60:40 molar ratioLi₂S:SiS₂.

As used herein, “SLOPS” includes, unless otherwise specified, a 60:40molar ratio of Li₂S:SiS₂ with 0.1-10 mol. % Li₃PO₄. In some examples,“SLOPS” includes Li₁₀Si₄Si₃ (50:50 Li₂S:SiS₂) with 0.1-10 mol. % Li₃PO₄.In some examples, “SLOPS” includes Li₂₆Si₇S₂₇ (65:35 Li₂S:SiS₂) with0.1-10 mol. % Li₃PO₄. In some examples, “SLOPS” includes Li₄SiS₄ (67:33Li₂S:SiS₂) with 0.1-5 mol. % Li₃PO₄. In some examples, “SLOPS” includesLi₁₄Si₃Si₃ (70:30 Li₂S:SiS₂) with 0.1-5 mol. % Li₃PO₄. In some examples,“SLOPS” is characterized by the formula (1−x)(60:40Li₂S:SiS₂)*(x)(Li₃PO₄), wherein x is from 0.01 to 0.99. As used herein,“LBS-PDX” refers to an electrolyte composition of Li₂S:B₂S₃:Li₃PO₄:LiXwhere X is a halogen (X═F, Cl, Br, I). The composition can includeLi₃BS₃ or Li₅B₇Si₃ doped with 0-30% lithium halide such as LiI and/or0-10% Li₃PO₄.

As used here, “LSS” refers to lithium silicon sulfide which can bedescribed as Li₂S—SiS₂, Li—SiS₂, Li—S—Si, and/or a catholyte consistingessentially of Li, S, and Si. LSS refers to an electrolyte materialcharacterized by the formula Li_(x)Si_(y)S_(z) where 0.33≤x≤0.5,0.1≤y≤0.2, 0.4≤z≤0.55, and it may include up to 10 atomic % oxygen. LSSalso refers to an electrolyte material comprising Li, Si, and S. In someexamples, LSS is a mixture of Li₂S and SiS₂. In some examples, the ratioof Li₂S:SiS₂ is about 90:10, about 85:15, about 80:20, about 75:25,about 70:30, about 2:1, about 65:35, about 60:40, about 55:45, or about50:50 molar ratio. LSS may be doped with compounds such as Li_(x)PO_(y),Li_(x)BO_(y), Li₄SiO₄, Li₃MO₄, Li₃MO₃, PS_(x), and/or lithium halidessuch as, but not limited to, LiI, LiCl, LiF, or LiBr, wherein 0<x≤5 and0<y≤5. LSS electrolytes may contain less than 5% or less than 10%oxygen.

As used here, “LTS” refers to a lithium tin sulfide compound which canbe described as Li₂S:SnS₂:As₂S₅, Li₂S—SnS₂, Li₂S—SnS, Li—S—Sn, and/or acatholyte consisting essentially of Li, S, and Sn. The composition maybe Li_(x)Sn_(y)S_(z) where 0.25≤x≤0.65, 0.05≤y≤0.2, and 0.25≤z≤0.65. Insome examples, LTS is a mixture of Li₂S and SnS₂ in the ratio of about80:20, about 75:25, about 70:30, about 2:1, or about 1:1 molar ratio.LTS may include up to 10 atomic % oxygen. LTS may be doped with Bi, Sb,As, P, B, Al, Ge, Ga, and/or In and/or lithium halides such as, but notlimited to, LiI, LiCl, LiF, or LiBr, As used herein, “LATS” refers toLTS, as used above, and further comprising Arsenic (As). LTS and LATSelectrolytes may contain less than 5% or less than 10% oxygen.

As used here, “LXPS” refers to a material characterized by the formulaLi_(a)MP_(b)S_(c), where M is Si, Ge, Sn, and/or Al, and where 2≤a≤8,0.5≤b≤2.5, 4≤c≤12. “LSPS” refers to an electrolyte materialcharacterized by the formula L_(a)SiP_(b)S_(c), where 2≤a≤8, 0.5≤b≤2.5,4≤c≤12. LSPS refers to an electrolyte material characterized by theformula L_(a)SiP_(b)S_(c), wherein, where 2≤a≤8, 0.5≤b≤4≤c≤12, d≤3. Inthese examples, the subscripts are selected so that the compound isneutrally charged. Exemplary LXPS materials are found, for example, inInternational Patent Application Publication No. PCT/US2014/038283,filed May 16, 2014 as PCT/US2014/038283, and titled SOLID STATECATHOLYTE OR ELECTROLYTE FOR BATTERY USING LI_(A)MP_(B)S_(C) (M=Si, Ge,AND/OR Sn), which is incorporated by reference herein in its entirety.Exemplary LXPS materials are found, for example, in U.S. Pat. Nos.9,172,114; 9,553,332; and 9,634,354, the contents of which areincorporated by reference in their entirety When M is Sn and Si—both arepresent—the LXPS material is referred to as LSTPS. As used herein,“LSTPSO,” refers to LSTPS that is doped with, or has, O present. In someexamples, “LSTPSO,” is a LSTPS material with an oxygen content between0.01 and 10 atomic %. “LSPS,” refers to an electrolyte material havingLi, Si, P, and S chemical constituents. As used herein “LSTPS,” refersto an electrolyte material having Li, Si, P, Sn, and S chemicalconstituents. As used herein, “LSPSO,” refers to LSPS that is dopedwith, or has, O present. In some examples, “LSPSO,” is a LSPS materialwith an oxygen content between 0.01 and 10 atomic %. As used herein,“LATP,” refers to an electrolyte material having Li, As, Sn, and Pchemical constituents. As used herein “LAGP,” refers to an electrolytematerial having Li, As, Ge, and P chemical constituents. As used herein,“LXPSO” refers to a catholyte material characterized by the formulaLi_(a)MP_(b)S_(c)O_(d), where M is Si, Ge, Sn, and/or Al, and where2≤a≤8, 0.5≤b≤2.5, 4≤c≤12, d<3. LXPSO refers to LXPS, as defined above,and having oxygen doping at from 0.1 to about 10 atomic %. LPSO refersto LPS, as defined above, and having oxygen doping at from 0.1 to about10 atomic %.

As used here, “LPS,” refers to an electrolyte having Li, P, and Schemical constituents. As used herein, “LPSO,” refers to LPS that isdoped with or has O present. In some examples, “LPSO,” is a LPS materialwith an oxygen content between 0.01 and 10 atomic %. LPS refers to anelectrolyte material that can be characterized by the formulaLi_(x)P_(y)S_(z) where 0.33≤x≤0.67, 0.07≤y≤0.2 and 0.4≤z≤0.55. LPS alsorefers to an electrolyte characterized by a product formed from amixture of Li₂S:P₂S₅ wherein the molar ratio is about 10:1, about 9:1,about 8:1, about 7:1, about 6:1 about 5:1, about 4:1, about 3:1, about7:3, about 2:1, or about 1:1. LPS also refers to an electrolytecharacterized by a product formed from a mixture of Li₂S:P₂S₅ whereinthe reactant or precursor amount of Li₂S is 95 atomic % and P₂₅₅ is 5atomic %. LPS also refers to an electrolyte characterized by a productformed from a mixture of Li₂S:P₂S₅ wherein the reactant or precursoramount of Li₂S is 90 atomic % and P₂S₅ is 10 atomic %. LPS also refersto an electrolyte characterized by a product formed from a mixture ofLi₂S:P₂S₅ wherein the reactant or precursor amount of Li₂S is 85 atomic% and P₂S₅ is 15 atomic %. LPS also refers to an electrolytecharacterized by a product formed from a mixture of Li₂S:P₂S₅ whereinthe reactant or precursor amount of Li₂S is 80 atomic % and P₂S₅ is 20atomic %. LPS also refers to an electrolyte characterized by a productformed from a mixture of Li₂S:P₂S₅ wherein the reactant or precursoramount of Li₂S is 75 atomic % and P₂S₅ is 25 atomic %. LPS also refersto an electrolyte characterized by a product formed from a mixture ofLi₂S:P₂S₅ wherein the reactant or precursor amount of Li₂S is 70 atomic% and P₂S₅ is 30 atomic %. LPS also refers to an electrolytecharacterized by a product formed from a mixture of Li₂S:P₂S₅ whereinthe reactant or precursor amount of Li₂S is 65 atomic % and P₂S₅ is 35atomic %. LPS also refers to an electrolyte characterized by a productformed from a mixture of Li₂S:P₂S₅ wherein the reactant or precursoramount of Li₂S is 60 atomic % and P₂S₅ is 40 atomic %. LPS may also bedoped with a lithium halide such as LiF, LiCl, LiBr, or LiI at a 0-40%molar content.

As used here, “LPSI” refers to an electrolyte material characterized bythe formula Li_(a)P_(b)S_(c)I_(d), wherein subscripts a, b, c, and d areselected so that the material is charge neutral, such as that describedin International Patent Application No. PCT/US2016/064492, filed Dec. 1,2016, which is incorporated herein by reference in its entirety for allpurposes; also U.S. patent application Ser. No. 15/367,103, filed Dec.1, 2016, which is incorporated herein by reference in its entirety forall purposes.

As used here, “LBS” refers to an electrolyte material characterized bythe formula Li_(a)B_(b)S_(c) and may include oxygen and/or a lithiumhalide (LiF, LiCl, LiBr, LiI) at 0-40 mol %. LBS electrolytes maycontain less than 5% or less than 10% oxygen.

As used here, “LPSO” refers to an electrolyte material characterized bythe formula Li_(x)P_(y)S_(z)O_(w) where 0.33≤x≤0.67, 0.07≤y≤0.2,0.4≤z≤0.55, 0≤w≤0.15. Also, LPSO refers to LPS, as defined above, thatincludes an oxygen content of from 0.01 to 10 atomic %. In someexamples, the oxygen content is 1 atomic %. In other examples, theoxygen content is 2 atomic %. In some other examples, the oxygen contentis 3 atomic %. In some examples, the oxygen content is 4 atomic %. Inother examples, the oxygen content is 5 atomic %. In some otherexamples, the oxygen content is 6 atomic %. In some examples, the oxygencontent is 7 atomic %. In other examples, the oxygen content is 8 atomic%. In some other examples, the oxygen content is 9 atomic %. In someexamples, the oxygen content is 10 atomic %.

As used herein, “LBHI” or “borohydride electrolyte” refers to anelectrolyte material with the formula Li_(a)B_(d)H_(c)I_(d)N_(c),wherein subscripts a, b, c, and d are selected so that the compound ischarge neutral, such as that described in U.S. Provisional PatentApplication No. 62/411,464, entitled SEPARATORS INCLUDING LITHIUMBOROHYDRIDE AND COMPOSITE SEPARATORS OF LITHIUM-STUFFED GARNET ANDLITHIUM BOROHYDRIDE which is incorporated herein by reference.

As used herein, the phrase “wherein the electrolyte separator protectsthe Li metal negative electrode from exposure to the polymer or to thesolvent,” refers to the barrier that the separator provides and whichprevents polymer or solvent from contacting the Li metal such that thepolymer or solvent can chemically react with the Li metal. In someexample, the barrier is the seal that the electrolyte separator makeswith the Li metal anode.

As used herein, the phrase “wherein the bonding layer lowers theinterfacial impedance between the electrolyte separator and the positiveelectrode than it otherwise would be in the absence of the bondinglayer,” refers to the observation that when a conventional cathode ispressed onto a garnet surface the total measured cell impedance is veryhigh, whereas when a bonding layer as set forth herein is present and incontact with the cathode, the impedance is reduced. In some examples,the bonding layer lowers the interfacial impedance at the interfacebetween the electrolyte membrane and the positive electrode by a factorof 1, 2, 10, 100, or 1000× with respect to the interfacial impedance atthe interface between the electrolyte membrane and the positiveelectrode when a bonding layer is not positioned between, theelectrolyte membrane and the positive electrode.

III. Compositions

In some examples, set forth herein is a free standing film, as definedabove, which further includes a gel electrolyte, wherein the gelelectrolyte comprises a lithium salt, a polymer, and a solvent.

In some examples, the gel electrolyte includes a lithium salt, apolymer, and a solvent. In some examples, the polymer is selected fromthe group consisting of polyacrylonitrile (PAN), polypropylene,polyethylene oxide (PEO), polymethyl methacrylate (PMMA), polyvinylchloride (PVC), polyvinyl pyrrolidone (PVP), polyethylene oxidepoly(allyl glycidyl ether) PEO-AGE, polyethylene oxide2-methoxyethoxy)ethyl glycidyl ether (PEO-MEEGE), polyethylene oxide2-methoxyethoxy)ethyl glycidyl poly(allyl glycidyl ether)(PEO-MEEGE-AGE), polysiloxane, polyvinylidene fluoride (PVDF),polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), and rubbers suchas ethylene propylene (EPR), nitrile rubber (NPR),styrene-butadiene-rubber (SBR), polybutadiene polymer, polybutadienerubber (PB), polyisobutadiene rubber (PIB), polyisoprene rubber (PI),polychloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR),polyethyl acrylate (PEA), polyvinylidene fluoride (PVDF), orpolyethylene (e.g., low density linear polyethylene).

In certain examples, the polymer in the gel electrolyte ispolyacrylonitrile (PAN) or polyvinylidene fluoride hexafluoropropylene(PVDF-HFP). In certain examples, the polymer in the gel electrolyte is acombination of polyacrylonitrile (PAN) and polyvinylidene fluoridehexafluoropropylene (PVDF-HFP). In certain examples, the polymer in thegel electrolyte is PAN, PVDF-HFP, PVDF-HFP and PAN, PMMA, PVC, PVP, PEO,or combinations thereof. In certain examples, the polymer in the gelelectrolyte is PAN. In certain examples, the polymer in the gelelectrolyte is PVDF-HFP. In certain examples, the polymer in the gelelectrolyte is PVDF-HFP. In certain examples, the polymer in the gelelectrolyte is PMMA. In certain examples, the polymer in the gelelectrolyte is PVC. In certain examples, the polymer in the gelelectrolyte is PVP. In certain examples, the polymer in the gelelectrolyte is PEO. In certain examples, the lithium salt in the gelelectrolyte is a lithium salt is selected from LiPF₆, Lithiumbis(oxalato)borate (LiBOB), Lithium bis(perfluoroethanesulfonyl)imide(LIBETI), LiTFSi, LiBF₄, LiClO₄, LiAsF₆, LiFSI, LiAsF₆, or LiI. Incertain examples, the lithium salt in the gel electrolyte is LiPF₆. Incertain examples, the lithium salt in the gel electrolyte is LiBOB. Incertain examples, the lithium salt in the gel electrolyte is LiTFSi. Incertain examples, the lithium salt in the gel electrolyte is LiBF₄. Incertain examples, the lithium salt in the gel electrolyte is LiClO₄. Incertain examples, the lithium salt in the gel electrolyte is LiAsF₆. Incertain examples, the lithium salt in the gel electrolyte is LiI. Incertain examples, the lithium salt in the gel electrolyte is LiBF₄ Incertain examples, several lithium salts may be present simultaneously indifferent concentrations. In some examples, the concentration is about0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1.0, about 1.1,about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about1.8, about 1.9 or about 2.0 M. In certain examples, the gel electrolytemay contain two salts selected from LiPF₆, LiBOB, LiTFSi, LiBF₄, LiClO₄,LiAsF₆, LiFSI, LiAsF₆, or LiI. In certain examples, the gel electrolytemay contain three salts selected from LiPF₆, LiBOB, LiTFSi, LiBF₄,LiClO₄, LiAsF₆, LiFSI, LiAsF₆, or LiI.

In certain examples, the lithium salt in the gel electrolyte is alithium salt is selected from LiPF₆, LiBOB, and LFTSi.

In certain examples, the lithium salt in the gel electrolyte is LiPF₆ ata concentration of 0.5 M to 2M. In some examples, the concentration is0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8,1.9 or 2.0M.

In certain examples, the lithium salt in the gel electrolyte is LiTFSIat a concentration of 0.5 M to 2M. In some examples, the concentrationis 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8,1.9 or 2.0M

In certain examples, the lithium salt in the gel electrolyte is presentat a concentration from 0.01 M to 10 M. In some examples, theconcentration is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1,1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5,2.6, 2.7, 2.8, 2.9, 3.0, 3.3, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9,2.0, 0.3, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 3.0, 3.1, 3.2, 3.3,3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7,5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1,7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.8, 8.4, 8.5,8.6, 8.7, 8.8, 8.9, 9.9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9,10.0 M.

In certain examples, the solvent in the gel is selected from ethylenecarbonate (EC), diethylene carbonate, diethyl carbonate, dimethylcarbonate (DMC), ethyl-methyl carbonate (EMC), propylmethyl carbonate,nitroethyl carbonate, propylene carbonate (PC), diethyl carbonate (DEC),methyl propyl carbonate (MPC), 2,5-Dioxahexanedioic Acid Dimethyl Ester,tetrahydrofuran (THF), γ-Butyrolactone (GBL), fluoroethylene carbonate(FEC), fluoromethyl ethylene carbonate (FMEC), trifluoroethyl methylcarbonate (F-EMC), fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-Tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE), fluorinated cyclic carbonate (F-AEC), dioxolane,prop-1-ene-1,3-sultone (PES), sulfolane, acetonitrile (ACN),succinonitrile (SN), Pimelonitrile, Suberonitrile, propionitrile,Propanedinitrile, glutaronitrile (GLN), adiponitrile (ADN),hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, Methylene methanedisulfonate, dimethyl sulfate, dimethylsulfoxide (DMSO), ethyl acetate, methyl butyrate, dimethyl ether (DME),diethyl ether, dioxolane, gamma butyl-lactone, Methyl benzoate,2-methyl-5-oxooxolane-2-carbonitrile, or combinations thereof.

In certain examples, the solvent is selected from methylene carbonate(EC). In certain examples, the solvent is a mixture of EC withsulfolane, EC with EMC, EC with PC, EC with DMC, EC with MPC, EC withDEC, EC with GBL, or EC with PES. The mixture ratio of EC to the othercomponent may be about 8:2, about 7:3, about 6:4, about 5:5, about 4:6,about 3:7, or about 2:8.

In certain examples, the solvent is selected from diethylene carbonate.

In certain examples, the solvent is selected from diethyl carbonate. Incertain examples, the solvent is selected from dimethyl carbonate (DMC).

In certain examples, the solvent is selected from ethyl-methyl carbonate(EMC).

In certain examples, the solvent is selected from tetrahydrofuran (THF),γ-Butyrolactone (GBL).

In certain examples, the solvent is selected from fluoroethylenecarbonate (FEC).

In certain examples, the solvent is selected from fluoromethyl ethylenecarbonate (FMEC).

In certain examples, the solvent is selected from trifluoroethyl methylcarbonate (F-EMC).

In certain examples, the solvent is selected from fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane (F-EPE). F-EPEmay be referred to as1,1,2,2-Tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane.

In certain examples, the solvent is selected from fluorinated cycliccarbonate (F-AEC).

In certain examples, the solvent is selected from propylene carbonate(PC).

In certain examples, the solvent is selected from dioxolane.

In certain examples, the solvent is selected from acetonitrile (ACN).

In certain examples, the solvent is selected from succinonitrile (SN).In certain examples, the solvent is SN mixed with GLN, SN mixed withacetonitrile, SN mixed with butyronitrile, SN mixed with Hexanenitrile,SN mixed with Benzonitrile, SN mixed with PES, or SN mixed with GBL. Themixture ratio of SN to the other component may be about 8:2, about 7:3,about 6:4, about 5:5, about 4:6, about 3:7, or about 2:8.

In certain examples, the solvent is selected from adiponitrile.

In certain examples, the solvent is selected from hexanedinitrile.

In certain examples, the solvent is selected from pentanedinitrile.

In certain examples, the solvent is selected from acetophenone.

In certain examples, the solvent is selected from isophorone.

In certain examples, the solvent is selected from benzonitrile.

In certain examples, the solvent is selected from dimethyl sulfate.

In certain examples, the solvent is selected from dimethyl sulfoxide(DMSO).

In certain examples, the solvent is selected from ethyl-methylcarbonate.

In certain examples, the solvent is selected from ethyl acetate.

In certain examples, the solvent is selected from methyl butyrate

In certain examples, the solvent is selected from dimethyl ether (DME).

In certain examples, the solvent is selected from diethyl ether.

In certain examples, the solvent is selected from propylene carbonate.

In certain examples, the solvent is selected from dioxolane.

In certain examples, the solvent is selected from glutaronitrile.

In certain examples, the solvent is selected from gamma butyl-lactone.

In certain examples, the solvent is a 1:1 w/w mixture of EC:PC.

In certain examples, the solvent is PES.

In certain examples, the solvent is present in the bonding layer (e.g.,the gel electrolyte which is the bonding layer) as a residual amount. Insome examples, the residual amount is the amount of solvent remainingafter the bonding layer is dried. In some examples, the residual amountis the amount of solvent remaining after the bonding layer is driedafter the bonding layer is made. In some examples, the residual amountis the amount of solvent remaining after the bonding layer isspin-coated onto a substrate and dried. In some examples, the residualamount is the minimum amount of solvent required to solvate the lithiumsalt. For example, in certain examples, the lithium salt in the gelelectrolyte is LiPF₆ at a concentration of 0.5 M to 2M. To prepare thisgel electrolyte, a solvent such as a combination of EC:DMC in a 1:1 v/vratio may be used. In this solvent, LiPF₆ is dissolved at aconcentration of 0.5 M to 2M. Next, the bonding layer is deposited ontoa substrate or onto a solid state electrolyte and allowed to dry. Oncethe evaporation of solvent is no longer appreciable at room temperature,the amount of solvent remaining in the gel is considered the residualamount.

In some examples, the gel may further include additives for the purposeof mitigating gas production during cycling or storage, for improvingvoltage or thermal stability, or for passivating active materials,current collectors, or other components. Additives are known in the art.Some examples may include vinylene carbonate (VC), methylene methanedisulfonate (MMDS), tris(trimethylsilyl) phosphate, fluoroethylenecarbonate (FEC), bis(2,2,2-trifluoroethyl) carbonate (TFEC) and/or othercompounds known in the art.

In some examples, the gel may further include structural reinforcementssuch as fibers or particles of a higher modulus material. The highermodulus material may be a ceramic such as Al₂O₃, MgO, SiO₂, SiN_(x),wherein x is selected so that the compound is charge neutral, and thelike.

In some examples, the water content in the solvents is less than 200ppm, or less than 150 ppm, or less than 100 ppm, or less than 60 ppm, orless than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than20 ppm, or less than 10 ppm.

In yet other examples, the film lowers the interfacial impedance betweenan electrolyte separator and a positive electrode, when positionedbetween and directly in contact with an electrolyte separator and apositive electrode.

In some examples, the gel electrolyte is prepared by mixing thecomponents of the gel electrolyte together and spin-casting the mixtureonto a substrate. In some examples, the spin-casting is used to preparea thin film of gel electrolyte. In some examples, the thin film of gelelectrolyte is prepared by spin-casting the electrolyte solution at1000-3000 RPMs. In some examples, the gel is drop-cast onto thesubstrate. In some examples, the gel is slot-die cast or doctor-bladedonto a substrate. The substrate may be a sacrificial substrate, theseparator electrolyte, or the cathode. As used herein, the gel mayinclude a one-stage gel. As used herein, the gel may include a two-stagegel.

IV. Electrochemical Cells

In some examples, set forth herein is an electrochemical stack,including a lithium metal (Li) negative electrode, a positive electrode,and an electrolyte separator in direct contact with the Li metalnegative electrode, and a gel electrolyte (also referred to as a bondinglayer) comprising a lithium salt, a polymer, and a solvent; wherein thebonding layer directly contacts, and is positioned between, theelectrolyte separator and the positive electrode; and wherein theelectrolyte separator protects the Li metal negative electrode fromexposure to the polymer or to the solvent in the bonding layer.

In some examples, in a fully charged state, the Li negative electrodeincludes a layer of Li metal having a thickness from 1 nm to 50 μm. Insome examples, the Li metal has a thickness from 10 μm to 50 μm. In someexamples, the Li metal has a thickness from 25 μm to 50 μm.

In some examples, in a fully discharged state, the Li negative electrodeincludes a layer of Li metal having a thickness of about 1 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 2 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 3 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 4 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 5 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 6 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 7 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 8 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 9 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 10 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 11 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 12 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 13 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 14 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 15 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 16 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 17 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 18 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 19 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 20 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 21 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 22 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 23 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 24 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 25 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 26 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 27 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 28 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 29 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 30 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 41 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 42 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 43 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 44 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 45 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 46 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 47 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 48 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 49 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 50 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 51 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 52 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 53 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 54 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 55 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 56 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 57 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 58 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 59 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 60 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 60 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 61 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 62 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 63 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 64 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 66 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 66 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 67 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 68 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 69 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 70 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 71 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 72 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 73 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 74 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 77 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 76 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 77 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 78 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 79 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 80 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 81 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 82 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 83 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 84 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 85 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 86 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 87 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 88 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 89 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 90 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 91 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 92 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 93 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 94 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 99 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 96 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 97 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 98 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 99 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 100 nm.

In some examples, in a fully discharged state, the Li negative electrodeincludes a layer of Li metal having a thickness of about 110 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 120 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 130 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 140 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 150 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 160 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 170 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 180 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 190 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 200 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 210 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 220 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 230 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 240 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 250 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 260 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 270 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 280 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 290 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 300 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 310 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 320 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 330 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 340 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 350 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 360 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 370 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 380 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 390 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 400 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 410 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 420 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 430 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 440 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 450 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 460 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 470 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 480 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 490 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 500 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 510 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 520 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 530 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 540 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 550 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 560 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 570 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 580 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 590 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 600 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 610 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 620 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 630 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 640 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 650 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 660 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 670 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 680 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 690 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 700 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 710 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 720 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 730 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 740 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 750 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 760 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 770 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 780 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 790 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 800 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 810 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 820 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 830 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 840 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 850 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 860 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 870 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 880 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 890 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 900 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 910 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 920 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 930 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 940 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 950 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 960 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 970 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 980 nm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 990 nm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 1000 nm.

In some examples, in a fully discharged state (0% rated SOC), the Linegative electrode includes a layer of Li metal having a thickness ofabout 1 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 2 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 3 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 4 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 5 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 6 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 7 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 8 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 9 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 10 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 11 μm. In some examples, the Li negative electrode includes alayer of Li metal having a thickness of about 12 μm. In some examples,the Li negative electrode includes a layer of Li metal having athickness of about 13 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 14 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 15 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 16 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 17 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 18 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 19 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 20 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 21 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 22 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 23 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 24 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 25 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 26 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 27 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 28 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 29 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 30 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 41 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 42 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 43 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 44 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 45 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 46 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 47 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 48 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 49 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 50 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 51 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 52 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 53 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 54 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 55 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 56 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 57 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 58 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 59 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 60 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 60 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 61 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 62 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 63 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 64 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 66 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 66 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 67 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 68 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 69 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 70 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 71 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 72 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 73 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 74 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 77 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 76 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 77 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 78 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 79 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 80 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 81 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 82 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 83 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 84 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 85 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 86 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 87 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 88 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 89 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 90 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 91 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 92 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 93 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 94 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 99 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 96 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 97 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 98 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 99 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 100 μm.

In some examples, in a fully charged state (100% rated SOC), the Linegative electrode includes a layer of Li metal having a thickness ofabout 1 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 2 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 3 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 4 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 5 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 6 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 7 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 8 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 9 μm. In some examples, the Li negative electrode includes a layerof Li metal having a thickness of about 10 μm. In some examples, the Linegative electrode includes a layer of Li metal having a thickness ofabout 11 μm. In some examples, the Li negative electrode includes alayer of Li metal having a thickness of about 12 μm. In some examples,the Li negative electrode includes a layer of Li metal having athickness of about 13 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 14 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 15 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 16 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 17 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 18 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 19 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 20 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 21 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 22 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 23 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 24 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 25 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 26 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 27 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 28 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 29 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 30 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 41 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 42 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 43 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 44 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 45 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 46 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 47 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 48 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 49 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 50 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 51 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 52 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 53 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 54 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 55 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 56 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 57 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 58 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 59 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 60 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 60 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 61 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 62 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 63 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 64 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 66 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 66 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 67 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 68 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 69 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 70 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 71 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 72 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 73 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 74 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 77 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 76 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 77 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 78 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 79 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 80 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 81 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 82 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 83 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 84 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 85 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 86 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 87 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 88 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 89 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 90 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 91 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 92 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 93 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 94 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 99 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 96 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 97 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 98 μm. In some examples, the Li negative electrodeincludes a layer of Li metal having a thickness of about 99 μm. In someexamples, the Li negative electrode includes a layer of Li metal havinga thickness of about 100 μm.

In some examples, the Li negative electrode includes a layer of Li metalhaving a thickness from 1 nm to 50 μm in the charged state.

In some examples, the electrolyte separator has a surface roughness Raor Rt, on at least one surface, from about 0.1 μm to 10 μm. In otherexamples, the electrolyte separator has a surface roughness, on at leastone surface, from about 0.1 μm to 5 μm. In other examples, theelectrolyte separator has a surface roughness, on at least one surface,from about 0.1 μm to 2 μm. In some examples, the electrolyte has asurface roughness from about 0.1 μm to 10 μm at the surface thatinterfaces the electrolyte separator and the Li metal negativeelectrode.

In some examples, the electrolyte separator has a density greater than95% of its theoretical density. In other examples, the electrolyteseparator has a density greater than 95% of its theoretical density asdetermined by scanning electron microscopy (SEM).

In certain examples, the electrolyte separator has a density greaterthan 95% of its theoretical density as measured by the Archimedesmethod.

In some examples, the electrolyte separator has a surface flatness of0.1 μm to about 50 μm.

In some examples, the polymer in the bonding layer is selected from thegroup consisting of polyacrylonitrile (PAN), polypropylene, polyethyleneoxide (PEO), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC),polyvinyl pyrrolidone (PVP), polyethylene oxide poly(allyl glycidylether) PEO-AGE, polyethylene oxide 2-methoxyethoxy)ethyl glycidyl ether(PEO-MEEGE), polyethylene oxide 2-methoxyethoxy)ethyl glycidylpoly(allyl glycidyl ether) (PEO-MEEGE-AGE), polysiloxane, polyvinylidenefluoride (PVDF), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP),and rubbers such as ethylene propylene (EPR), nitrile rubber (NPR),styrene-butadiene-rubber (SBR), polybutadiene polymer, polybutadienerubber (PB), polyisobutadiene rubber (PIB), polyisoprene rubber (PI),polychloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR),polyethyl acrylate (PEA), polyvinylidene fluoride (PVDF), orpolyethylene (e.g., low density linear polyethylene). In certainexamples, the polymer in the bonding layer is polyacrylonitrile (PAN) orpolyvinylidene fluoride hexafluoropropylene (PVDF-HFP). In certainexamples, the polymer in the bonding layer is PAN, PVDF-HFP, PVDF-HFPand PAN, PMMA, PVC, PVP, PEO, or combinations thereof.

In some examples, the lithium salt in the bonding layer is selected fromLiPF₆, LiBOB, LiTFSi, LiBF₄, LiClO₄, LiAsF₆, LiFSI, LiAsF₆, LiClO₄, LiI,or LiBF₄. In certain examples, the lithium salt in the bonding layer isselected from LiPF₆, LiBOB, or LFTSi.

In certain examples, the lithium salt in the bonding layer is LiPF₆ at aconcentration of 0.5 M to 2M. In certain examples, the lithium salt inthe bonding layer is LiTFSI at a concentration of 0.5 M to 2M. Incertain examples, the lithium salt in the bonding layer is present at aconcentration from 0.01 M to 10 M.

In some examples, the solvent in the bonding layer is selected fromethylene carbonate (EC), diethylene carbonate, diethyl carbonate,dimethyl carbonate (DMC), ethyl-methyl carbonate (EMC), tetrahydrofuran(THF), γ-Butyrolactone (GBL), fluoroethylene carbonate (FEC),fluoromethyl ethylene carbonate (FMEC), trifluoroethyl methyl carbonate(F-EMC), fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-Tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE), fluorinated cyclic carbonate (F-AEC), propylene carbonate (PC),dioxolane, acetonitrile (ACN), succinonitrile, adiponitrile,hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, dimethyl sulfate, dimethyl sulfoxide (DMSO) ethyl-methylcarbonate, ethyl acetate, methyl butyrate, dimethyl ether (DME), diethylether, propylene carbonate, dioxolane, glutaronitrile, gammabutyl-lactone, PES, sulfolane, or combinations thereof. In someexamples, the solvent in the bonding layer is the same as the solvent inthe catholyte gel.

In other examples, the solvent is a 1:1 w/w mixture of EC:PC.

In yet other examples, the solvent in the bonding layer is present as aresidual amount. In some examples, the residual amount is the amount ofsolvent remaining after the bonding layer is dried. In other examples,the residual amount is the minimum amount of solvent required to solvatethe lithium salt.

In some examples, the bonding layer lowers the interfacial impedancebetween the electrolyte separator and the positive electrode than itotherwise would be in the absence of the bonding layer.

In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 50 Ω·cm²at 50° C., when the bonding layer is positioned between and in directcontact with the oxide electrolyte separator and the positive electrode.In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 25 Ω·cm²at 50° C. In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 10 Ω·cm²at 50° C. In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 5 Ω·cm² at50° C. In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 5 Ω·cm² at30° C. In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 5 Ω·cm² at20° C. In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 5 Ω·cm² at10° C. In some examples, the interfacial impedance between the oxideelectrolyte separator and the positive electrode is less than 5 Ω·cm² at0° C.

In some examples, the positive electrode includes a lithiumintercalation material, a lithium conversion material, or both a lithiumintercalation material and a lithium conversion material. In someexamples, the lithium intercalation material is selected from a nickelmanganese cobalt oxide Li(NiCoMn)O₂, (NMC), a nickel cobalt aluminumoxide (NCA), Li(NiCoAl)O₂, a lithium cobalt oxide (LCO), a lithiummanganese cobalt oxide (LMCO), a lithium nickel manganese cobalt oxide(LMNCO), a lithium nickel manganese oxide (LNMO), LiMn₂O₄, LiCoO₂,LiMn₂-aNi_(a)O₄, wherein a is from 0 to 2, or LiMPO₄, wherein M is Fe,Ni, Co, or Mn. In others, the lithium conversion material is selectedfrom the group consisting of FeF₂, NiF₂, FeO_(x)F_(3-2x), FeF₃, MnF₃,CoF₃, CuF₂ materials, alloys thereof, and combinations thereof. Inothers, the conversion material is doped with other transition metalfluorides or oxides.

In some examples, the positive electrode further includes a catholyte.In some examples, the catholyte is a gel electrolyte. In some examples,the positive electrode includes a gel catholyte. In some examples, thepositive electrode includes a gel catholyte comprising, a solventselected from the group consisting of ethylene carbonate (EC), propylenecarbonate (PC), dimethyl carbonate (DMC), methylene carbonate, andcombinations thereof; a polymer selected from the group consisting ofPVDF-HFP and PAN; and a salt selected from the group consisting ofLiPF₆, LiBOB, and LFTSi.

In some examples, the positive electrode further includes a binderpolymer selected from the group consisting of polypropylene (PP),atactic polypropylene (aPP), isotactive polypropylene (iPP), ethylenepropylene rubber (EPR), ethylene pentene copolymer (EPC), polyethyleneoxide (PEO), PEO block copolymers, polyethylene glycol, polyisobutylene(PIB), styrene butadiene rubber (SBR), a polyolefin,polyethylene-co-poly-1-octene (PE-co-PO) copolymer, PE-co-poly(methylenecyclopentane) (PE-co-PMCP) copolymer, stereoblock polypropylenes,polypropylene polymethylpentene copolymer, acrylics, acrylates,polyvinyl butyral, vinyl polymers, cellulose polymers, resins, polyvinylalcohol, polymethyl methacrylate, polyvinyl pyrrolidone, polyacrylamide,silicone, PVDF, PVDF-HFP, PAN and combinations thereof. In someexamples, the binder polymer is the same polymer as that which is usedas a polymer in the bonding layer. In some examples, the positiveelectrode and/or bonding layer may include poly-ethylene carbonate,polyphenylene sulfide, and/or poly-propylene carbonate.

In some examples, the positive electrode includes an electronicallyconductive source of carbon.

In some examples, the positive electrode includes a solid catholyte anda lithium intercalation material or a lithium conversion material;wherein each of the catholyte and lithium intercalation material or alithium conversion material independently has a d₅₀ particle size fromabout 0.1 μm to 5 μm.

In some examples, the electrolyte separator is selected from the groupconsisting of a lithium-stuffed garnet, a sulfide electrolyte doped withoxygen, a sulfide electrolyte comprising oxygen, a lithium aluminumtitanium oxide, a lithium aluminum titanium phosphate, a lithiumaluminum germanium phosphate, a lithium aluminum titanium oxy-phosphate,a lithium lanthanum titanium oxide perovskite, a lithium lanthanumtantalum oxide perovskite, a lithium lanthanum titanium oxideperovskite, an antiperovskite, a LISICON, a LI—S—O—N, lithium aluminumsilicon oxide, a Thio-LISICON, a lithium-substituted NASICON, a LIPON,or a combination, mixture, or multilayer thereof. In some examples, theelectrolyte separator is an oxide electrolyte separator.

In some examples, the oxide electrolyte separator is a lithium-stuffedgarnet.

In some examples, the electrolyte separator is a sulfide electrolytedoped with oxygen,

In some examples, the electrolyte separator is a sulfide electrolytecomprising oxygen.

In some examples, the electrolyte separator is a lithium aluminumtitanium oxide.

In some examples, the electrolyte separator is a lithium aluminumtitanium phosphate.

In some examples, the electrolyte separator is a lithium aluminumgermanium phosphate.

In some examples, the electrolyte separator is a lithium aluminumtitanium oxy-phosphate.

In some examples, the electrolyte separator is a lithium lanthanumtitanium oxide perovskite.

In some examples, the electrolyte separator is a lithium lanthanumtantalum oxide perovskite.

In some examples, the electrolyte separator is a lithium lanthanumtitanium oxide perovskite.

In some examples, the electrolyte separator is an antiperovskite.

In some examples, the electrolyte separator is a LISICON.

In some examples, the electrolyte separator is a LI—S—O—N.

In some examples, the electrolyte separator is a lithium aluminumsilicon oxide.

In some examples, the electrolyte separator is a Thio-LISICON

In some examples, the electrolyte separator is a lithium-substitutedNASICON.

In some examples, the electrolyte separator is a LIPON

In some examples, the lithium lanthanum titanium oxide is characterizedby the empirical formula, Li_(3x)La_(2/3-x)TiO₃, wherein x is a rationalnumber from 0 to ⅔.

In some examples, the lithium lanthanum titanium oxide is characterizedby the empirical formula, Li_(3x)La_(2/3-x)Ti_(j)Ta_(k)O₃, wherein x isa rational number from 0 to ⅔, and wherein subscripts j+k=1.

In some examples, the lithium lanthanum titanium oxide is characterizedby a perovskite crystal structure.

In some examples, the antiperovskite is Li₃₀Cl.

In some examples, the LISICON is Li(Me′x,Me″y)(PO₄) wherein Me′ and Me″are selected from Si, Ge, Sn or combinations thereof; and wherein 0≤x≤1;wherein 0≤y≤1, and wherein x+y=1.

In some examples, the LISICON is Li_(4−x)Ge_(1−x)P_(x)S₄ where0.2≤x≤0.8. In some examples, x is 0.2. In some examples, x is 0.25. Insome examples, x is 0.3. In some examples, x is 0.35. In some examples,x is 0.4. In some examples, x is 0.45. In some examples, x is 0.5. Insome examples, x is 0.55. In some examples, x is 0.6. In some examples,x is 0.65. In some examples, x is 0.7. In some examples, x is 0.75. Insome examples, x is 0.8. In some examples, the Thio-LISICON isLi_(3.25)Ge_(0.25)P_(0.75)S₄.

In some examples, the Thio-LISICON is Li_(4−x)M_(1−x)P_(x)S₄ orLi₁₀MP₂S₁₂, wherein M is selected from Si, Ge, Sn, or combinationsthereof; and wherein 0≤x≤1.

In some examples, the lithium aluminum titanium phosphate isLi_(1+x)Al_(x)Ti_(2−x)(PO₄), wherein 0≤x≤2.

In some examples, the lithium aluminum germanium phosphate isLi_(1.5)Al_(0.5)Ge_(1.5)(PO₄).

In some examples, the LI—S—O—N is Li_(x)S_(y)O_(z)N_(w), wherein x, y,z, and w, are a rational number from 0.01 to 1.

In some examples, the electrolyte separator is characterized by thechemical formula Li_(x)La₃Zr₂O_(h)+yAl₂O₃, wherein 3≤x≤8, 0≤y≤1, and6≤h≤15; and wherein subscripts x and h, and coefficient y is selected sothat the electrolyte separator is charge neutral.

In some examples, the electrolyte separator isolates the positiveelectrode from the negative electrode by preventing electron transportbetween the two electrodes.

In some examples, the electrolyte separator has a top or bottom surfacethat has less than 5 atomic % of an amorphous material comprising carbonand oxygen. In some examples, the amorphous material is lithiumcarbonate, lithium hydroxide, lithium oxide, lithium peroxide, a hydratethereof, an oxide thereof, or a combination thereof. In some of theseexamples, the electrolyte separator has a top or bottom surface whichonly includes material which is the same as the material in the bulk.

In some examples, the separator is a borohydride electrolyte or an LPSIelectrolyte or a composite electrolyte.

In some examples, the bonding layer is characterized by a thickness ofabout 1 nm to about 5 μm.

In some examples, set forth herein is a bonding layer having a thicknessof about 1 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 2 nm. In some examples, set forth herein isa bonding layer having a thickness of about 3 nm. In some examples, setforth herein is a bonding layer having a thickness of about 4 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 5 nm. In some examples, set forth herein is a bonding layer havinga thickness of about 6 nm. In some examples, set forth herein is abonding layer having a thickness of about 7 nm. In some examples, setforth herein is a bonding layer having a thickness of about 8 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 9 nm. In some examples, set forth herein is a bonding layer havinga thickness of about 10 nm. In some examples, set forth herein is abonding layer having a thickness of about 11 nm. In some examples, setforth herein is a bonding layer having a thickness of about 12 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 13 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 14 nm. In some examples, set forth herein isa bonding layer having a thickness of about 15 nm. In some examples, setforth herein is a bonding layer having a thickness of about 16 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 17 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 18 nm. In some examples, set forth herein isa bonding layer having a thickness of about 19 nm. In some examples, setforth herein is a bonding layer having a thickness of about 20 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 21 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 22 nm. In some examples, set forth herein isa bonding layer having a thickness of about 23 nm. In some examples, setforth herein is a bonding layer having a thickness of about 24 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 25 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 26 nm. In some examples, set forth herein isa bonding layer having a thickness of about 27 nm. In some examples, setforth herein is a bonding layer having a thickness of about 28 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 29 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 30 nm. In some examples, set forth herein isa bonding layer having a thickness of about 41 nm. In some examples, setforth herein is a bonding layer having a thickness of about 42 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 43 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 44 nm. In some examples, set forth herein isa bonding layer having a thickness of about 45 nm. In some examples, setforth herein is a bonding layer having a thickness of about 46 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 47 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 48 nm. In some examples, set forth herein isa bonding layer having a thickness of about 49 nm. In some examples, setforth herein is a bonding layer having a thickness of about 50 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 51 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 52 nm. In some examples, set forth herein isa bonding layer having a thickness of about 53 nm. In some examples, setforth herein is a bonding layer having a thickness of about 54 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 55 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 56 nm. In some examples, set forth herein isa bonding layer having a thickness of about 57 nm. In some examples, setforth herein is a bonding layer having a thickness of about 58 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 59 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 60 nm. In some examples, set forth herein isa bonding layer having a thickness of about 60 nm. In some examples, setforth herein is a bonding layer having a thickness of about 61 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 62 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 63 nm. In some examples, set forth herein isa bonding layer having a thickness of about 64 nm. In some examples, setforth herein is a bonding layer having a thickness of about 66 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 66 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 67 nm. In some examples, set forth herein isa bonding layer having a thickness of about 68 nm. In some examples, setforth herein is a bonding layer having a thickness of about 69 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 70 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 71 nm. In some examples, set forth herein isa bonding layer having a thickness of about 72 nm. In some examples, setforth herein is a bonding layer having a thickness of about 73 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 74 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 77 nm. In some examples, set forth herein isa bonding layer having a thickness of about 76 nm. In some examples, setforth herein is a bonding layer having a thickness of about 77 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 78 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 79 nm. In some examples, set forth herein isa bonding layer having a thickness of about 80 nm. In some examples, setforth herein is a bonding layer having a thickness of about 81 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 82 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 83 nm. In some examples, set forth herein isa bonding layer having a thickness of about 84 nm. In some examples, setforth herein is a bonding layer having a thickness of about 85 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 86 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 87 nm. In some examples, set forth herein isa bonding layer having a thickness of about 88 nm. In some examples, setforth herein is a bonding layer having a thickness of about 89 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 90 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 91 nm. In some examples, set forth herein isa bonding layer having a thickness of about 92 nm. In some examples, setforth herein is a bonding layer having a thickness of about 93 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 94 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 99 nm. In some examples, set forth herein isa bonding layer having a thickness of about 96 nm. In some examples, setforth herein is a bonding layer having a thickness of about 97 nm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 98 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 99 nm. In some examples, set forth herein isa bonding layer having a thickness of about 100 nm.

In some examples, set forth herein is a bonding layer having a thicknessof about 110 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 120 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 130 nm. In some examples,set forth herein is a bonding layer having a thickness of about 140 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 150 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 160 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 170 nm. In some examples,set forth herein is a bonding layer having a thickness of about 180 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 190 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 200 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 210 nm. In some examples,set forth herein is a bonding layer having a thickness of about 220 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 230 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 240 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 250 nm. In some examples,set forth herein is a bonding layer having a thickness of about 260 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 270 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 280 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 290 nm. In some examples,set forth herein is a bonding layer having a thickness of about 300 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 310 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 320 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 330 nm. In some examples,set forth herein is a bonding layer having a thickness of about 340 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 350 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 360 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 370 nm. In some examples,set forth herein is a bonding layer having a thickness of about 380 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 390 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 400 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 410 nm. In some examples,set forth herein is a bonding layer having a thickness of about 420 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 430 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 440 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 450 nm. In some examples,set forth herein is a bonding layer having a thickness of about 460 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 470 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 480 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 490 nm. In some examples,set forth herein is a bonding layer having a thickness of about 500 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 510 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 520 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 530 nm. In some examples,set forth herein is a bonding layer having a thickness of about 540 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 550 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 560 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 570 nm. In some examples,set forth herein is a bonding layer having a thickness of about 580 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 590 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 600 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 610 nm. In some examples,set forth herein is a bonding layer having a thickness of about 620 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 630 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 640 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 650 nm. In some examples,set forth herein is a bonding layer having a thickness of about 660 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 670 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 680 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 690 nm. In some examples,set forth herein is a bonding layer having a thickness of about 700 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 710 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 720 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 730 nm. In some examples,set forth herein is a bonding layer having a thickness of about 740 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 750 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 760 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 770 nm. In some examples,set forth herein is a bonding layer having a thickness of about 780 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 790 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 800 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 810 nm. In some examples,set forth herein is a bonding layer having a thickness of about 820 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 830 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 840 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 850 nm. In some examples,set forth herein is a bonding layer having a thickness of about 860 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 870 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 880 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 890 nm. In some examples,set forth herein is a bonding layer having a thickness of about 900 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 910 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 920 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 930 nm. In some examples,set forth herein is a bonding layer having a thickness of about 940 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 950 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 960 nm. In some examples, set forth hereinis a bonding layer having a thickness of about 970 nm. In some examples,set forth herein is a bonding layer having a thickness of about 980 nm.In some examples, set forth herein is a bonding layer having a thicknessof about 990 nm. In some examples, set forth herein is a bonding layerhaving a thickness of about 1000 nm.

In some examples, set forth herein is a bonding layer having a thicknessof about 1 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 2 μm. In some examples, set forth herein isa bonding layer having a thickness of about 3 μm. In some examples, setforth herein is a bonding layer having a thickness of about 4 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 5 μm. In some examples, set forth herein is a bonding layer havinga thickness of about 6 μm. In some examples, set forth herein is abonding layer having a thickness of about 7 μm. In some examples, setforth herein is a bonding layer having a thickness of about 8 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 9 μm. In some examples, set forth herein is a bonding layer havinga thickness of about 10 μm. In some examples, set forth herein is abonding layer having a thickness of about 11 μm. In some examples, setforth herein is a bonding layer having a thickness of about 12 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 13 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 14 μm. In some examples, set forth herein isa bonding layer having a thickness of about 15 μm. In some examples, setforth herein is a bonding layer having a thickness of about 16 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 17 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 18 μm. In some examples, set forth herein isa bonding layer having a thickness of about 19 μm. In some examples, setforth herein is a bonding layer having a thickness of about 20 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 21 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 22 μm. In some examples, set forth herein isa bonding layer having a thickness of about 23 μm. In some examples, setforth herein is a bonding layer having a thickness of about 24 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 25 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 26 μm. In some examples, set forth herein isa bonding layer having a thickness of about 27 μm. In some examples, setforth herein is a bonding layer having a thickness of about 28 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 29 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 30 μm. In some examples, set forth herein isa bonding layer having a thickness of about 41 μm. In some examples, setforth herein is a bonding layer having a thickness of about 42 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 43 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 44 μm. In some examples, set forth herein isa bonding layer having a thickness of about 45 μm. In some examples, setforth herein is a bonding layer having a thickness of about 46 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 47 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 48 μm. In some examples, set forth herein isa bonding layer having a thickness of about 49 μm. In some examples, setforth herein is a bonding layer having a thickness of about 50 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 51 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 52 μm. In some examples, set forth herein isa bonding layer having a thickness of about 53 μm. In some examples, setforth herein is a bonding layer having a thickness of about 54 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 55 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 56 μm. In some examples, set forth herein isa bonding layer having a thickness of about 57 μm. In some examples, setforth herein is a bonding layer having a thickness of about 58 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 59 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 60 μm. In some examples, set forth herein isa bonding layer having a thickness of about 60 μm. In some examples, setforth herein is a bonding layer having a thickness of about 61 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 62 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 63 μm. In some examples, set forth herein isa bonding layer having a thickness of about 64 μm. In some examples, setforth herein is a bonding layer having a thickness of about 66 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 66 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 67 μm. In some examples, set forth herein isa bonding layer having a thickness of about 68 μm. In some examples, setforth herein is a bonding layer having a thickness of about 69 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 70 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 71 μm. In some examples, set forth herein isa bonding layer having a thickness of about 72 μm. In some examples, setforth herein is a bonding layer having a thickness of about 73 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 74 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 77 μm. In some examples, set forth herein isa bonding layer having a thickness of about 76 μm. In some examples, setforth herein is a bonding layer having a thickness of about 77 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 78 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 79 μm. In some examples, set forth herein isa bonding layer having a thickness of about 80 μm. In some examples, setforth herein is a bonding layer having a thickness of about 81 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 82 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 83 μm. In some examples, set forth herein isa bonding layer having a thickness of about 84 μm. In some examples, setforth herein is a bonding layer having a thickness of about 85 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 86 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 87 μm. In some examples, set forth herein isa bonding layer having a thickness of about 88 μm. In some examples, setforth herein is a bonding layer having a thickness of about 89 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 90 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 91 μm. In some examples, set forth herein isa bonding layer having a thickness of about 92 μm. In some examples, setforth herein is a bonding layer having a thickness of about 93 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 94 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 99 μm. In some examples, set forth herein isa bonding layer having a thickness of about 96 μm. In some examples, setforth herein is a bonding layer having a thickness of about 97 μm. Insome examples, set forth herein is a bonding layer having a thickness ofabout 98 μm. In some examples, set forth herein is a bonding layerhaving a thickness of about 99 μm. In some examples, set forth herein isa bonding layer having a thickness of about 100 μm.

In some examples, the Li negative electrode is characterized by athickness of about 10 nm to about 50 μm.

In some examples, the oxide separator is characterized by a thickness ofabout 0.1 μm to about 150 μm. In some examples, oxide separator ischaracterized by a thickness of about 10 μm to about 50 μm.

In some examples, the bonding layer penetrates into the positiveelectrode. In other examples, bonding layer penetrates into the positiveelectrode at least 10% of the thickness of the positive electrode. Inother examples, bonding layer penetrates into the positive electrode atleast 9% of the thickness of the positive electrode. In other examples,bonding layer penetrates into the positive electrode at least 8% of thethickness of the positive electrode. In other examples, bonding layerpenetrates into the positive electrode at least 7% of the thickness ofthe positive electrode. In other examples, bonding layer penetrates intothe positive electrode at least 6% of the thickness of the positiveelectrode. In other examples, bonding layer penetrates into the positiveelectrode at least 5% of the thickness of the positive electrode. Inother examples, bonding layer penetrates into the positive electrode atleast 4% of the thickness of the positive electrode. In other examples,bonding layer penetrates into the positive electrode at least 3% of thethickness of the positive electrode. In other examples, bonding layerpenetrates into the positive electrode at least % of the thickness ofthe positive electrode. In other examples, bonding layer penetrates intothe positive electrode at least 1% of the thickness of the positiveelectrode.

In some examples, the bonding layer contacts the catholyte in thepositive electrode. In some examples, the bonding layer does not creeparound the electrolyte separator. In some examples, the bonding layerdoes not include components which volatilize and diffuse around theelectrolyte separator to contact the Li metal negative electrode.

In some examples, the solvent in the bonding layer have a vapor pressureless than about 80 Torr at 20° C. In some examples, the solvent in thebonding layer has a boiling point above 80° C. at one atmosphere.

In some examples, the oxide electrolyte separator is free of surfacedefects. In some examples, the electrolyte separator surface does notintersect a pore of greater than 5 μm.

In some examples, the diameter of the electrolyte separator is greaterthan the diameter of the lithium metal negative electrode.

In some examples, the diameter of the electrolyte separator is greaterthan the diameter of the lithium metal negative electrode by a factor of0.1, 0.2, 0.3, 0.4, 0.5, 0.6. 0.7, 0.8, 0.9, 1, 2.

In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by a factor of 0.1. In some examples, the diameter or area ofthe electrolyte separator is greater than the diameter or area of thelithium metal negative electrode by a factor of 0.2. In some examples,the diameter or area of the electrolyte separator is greater than thediameter or area of the lithium metal negative electrode by a factor of0.3. In some examples, the diameter or area of the electrolyte separatoris greater than the diameter or area of the lithium metal negativeelectrode by a factor of 0.4. In some examples, the diameter or area ofthe electrolyte separator is greater than the diameter or area of thelithium metal negative electrode by a factor of 0.5. In some examples,the diameter or area of the electrolyte separator is greater than thediameter or area of the lithium metal negative electrode by a factor of0.6. In some examples, the diameter or area of the electrolyte separatoris greater than the diameter or area of the lithium metal negativeelectrode by a factor of 0.7. In some examples, the diameter or area ofthe electrolyte separator is greater than the diameter or area of thelithium metal negative electrode by a factor of 0.8. In some examples,the diameter or area of the electrolyte separator is greater than thediameter or area of the lithium metal negative electrode by a factor of0.9. In some examples, the diameter or area of the electrolyte separatoris greater than the diameter or area of the lithium metal negativeelectrode by a factor of 1. In some examples, the diameter or area ofthe electrolyte separator is greater than the diameter or area of thelithium metal negative electrode by a factor of 2.

In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by at least a factor of 0.1. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the lithium metal negative electrode by at least a factor of 0.2. Insome examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by at least a factor of 0.3. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the lithium metal negative electrode by at least a factor of 0.4. Insome examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by at least a factor of 0.5. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the lithium metal negative electrode by at least a factor of 0.6. Insome examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by at least a factor of 0.7. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the lithium metal negative electrode by at least a factor of 0.8. Insome examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by at least a factor of 0.9. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the lithium metal negative electrode by at least a factor of 1. Insome examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the lithium metal negativeelectrode by at least a factor of 2.

In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by a factorof 0.1, 0.2, 0.3, 0.4, 0.5, 0.6. 0.7, 0.8, 0.9, 1, 2.

In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by a factorof 0.1. In some examples, the diameter or area of the electrolyteseparator is greater than the diameter or area of the positive electrodeby a factor of 0.2. In some examples, the diameter or area of theelectrolyte separator is greater than the diameter or area of thepositive electrode by a factor of 0.3. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the positive electrode by a factor of 0.4. In some examples, thediameter or area of the electrolyte separator is greater than thediameter or area of the positive electrode by a factor of 0.5. In someexamples, the diameter or area of the electrolyte separator is greaterthan the diameter or area of the positive electrode by a factor of 0.6.In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by a factorof 0.7. In some examples, the diameter or area of the electrolyteseparator is greater than the diameter or area of the positive electrodeby a factor of 0.8. In some examples, the diameter or area of theelectrolyte separator is greater than the diameter or area of thepositive electrode by a factor of 0.9. In some examples, the diameter orarea of the electrolyte separator is greater than the diameter or areaof the positive electrode by a factor of 1. In some examples, thediameter or area of the electrolyte separator is greater than thediameter or area of the positive electrode by a factor of 2.

In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by at leasta factor of 0.1. In some examples, the diameter or area of theelectrolyte separator is greater than the diameter or area of thepositive electrode by at least a factor of 0.2. In some examples, thediameter or area of the electrolyte separator is greater than thediameter or area of the positive electrode by at least a factor of 0.3.In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by at leasta factor of 0.4. In some examples, the diameter or area of theelectrolyte separator is greater than the diameter or area of thepositive electrode by at least a factor of 0.5. In some examples, thediameter or area of the electrolyte separator is greater than thediameter or area of the positive electrode by at least a factor of 0.6.In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by at leasta factor of 0.7. In some examples, the diameter or area of theelectrolyte separator is greater than the diameter or area of thepositive electrode by at least a factor of 0.8. In some examples, thediameter or area of the electrolyte separator is greater than thediameter or area of the positive electrode by at least a factor of 0.9.In some examples, the diameter or area of the electrolyte separator isgreater than the diameter or area of the positive electrode by at leasta factor of 1. In some examples, the diameter or area of the electrolyteseparator is greater than the diameter or area of the positive electrodeby at least a factor of 2.

In some examples, the width or diameter or area of the electrolyteseparator is greater than either of the diameter or area of the lithiummetal negative electrode or of the positive electrode. In otherexamples, the width or diameter of the electrolyte separator is greaterthan the width or diameter of the lithium metal negative electrode. Insome other examples, the width or diameter of the electrolyte separatoris greater than the width or diameter of the positive electrode. In someexamples, the width or diameter of the electrolyte separator is greaterthan both the width or diameter of the lithium metal negative electrodeand positive electrode. In other examples, the electrolyte separator hasrounded edges which protect the bonding layer, or its constituentcomponents, from creeping around the electrolyte separator. In yet otherexamples, the electrolyte separator has coated edges which protect thebonding layer from creeping around the electrolyte separator.

In some examples, the coated edges comprise a coating selected fromparylene, epoxy, polypropylene, polyethylene, alumina, Al₂O₃, ZrO₂,TiO₂, SiO₂, a binary oxide, a lithium carbonate species, La₂Zr₂O₇, or aglass, wherein the glass is selected from SiO₂—B₂O₃, or Al₂O₃. In someexamples, the electrolyte separator has tapered edges which protect thebonding layer from creeping around the electrolyte separator. In someexamples, the edges of the separator electrolyte have been selectivelytreated with heat (e.g. laser beam) or chemicals (e.g. plasma, water,acid, etc).

In some examples, set forth herein is an electrochemical stack having anelectrolyte separator which has a thickness between about 10 and 20 μm;a bonding layer which has a thickness between about 1 μm and 5 μm; and apositive electrode, exclusive of the current collector, which has athickness between about 5 μm and 150 μm.

In some examples, set forth herein is an electrochemical stack having anelectrolyte separator which has a thickness between about 10 and 50 μm;a bonding layer which has a thickness between about 1 μm and 5 μm; and apositive electrode, exclusive of the current collector, which has athickness between about 5 μm and 150 μm.

In some examples, set forth herein is an electrochemical stack having anelectrolyte separator which has a thickness between about 10 and 100 μm;a bonding layer which has a thickness between about 1 μm and 5 μm; and apositive electrode, exclusive of the current collector, which has athickness between about 5 μm and 150 μm.

In some examples, set forth herein is an electrochemical cell having apositive electrode, a negative electrode, and an electrolyte between thepositive and negative electrode, wherein the electrolyte includes anelectrolyte separator or membrane set forth herein.

In some examples, set forth herein is an electrochemical cell having anelectrolyte separator set forth herein, wherein the electrochemical cellfurther includes a gel electrolyte.

In some examples, set forth herein is an electrochemical cell having anelectrolyte separator set forth herein, wherein the electrochemical cellfurther includes a gel electrolyte between the positive electrode activematerial and the electrolyte separator.

In some examples, the gel electrolyte includes a solvent, a lithiumsalt, and a polymer.

In some of these examples, the solvent is ethylene carbonate, propylenecarbonate, diethylene carbonate, methylene carbonate, or a combinationthereof.

In some of these examples, the lithium salt is LiPF₆, LiBOB, or LFTSi.

In some of these examples, the polymer is PVDF-HFP.

In some of these examples, the gel includes PVDF with the solventdioxolane and the salt, lithium bis(trifluoromethane)sulfonimide(LiTFSI), at 1M concentration.

In some examples the polymer is polypropylene (PP), atacticpolypropylene (aPP), isotactive polypropylene (iPP), ethylene propylenerubber (EPR), ethylene pentene copolymer (EPC), polyisobutylene (PIB),styrene butadiene rubber (SBR), polyolefins,polyethylene-co-poly-1-octene (PE-co-PO), PE-co-poly(methylenecyclopentane) (PE-co-PMCP), poly methyl-methacrylate (and otheracrylics), acrylic, polyvinylacetacetal resin, polyvinylbutylal resin,PVB, polyvinyl acetal resin, stereoblock polypropylenes, polypropylenepolymethylpentene copolymer, polyethylene oxide (PEO), PEO blockcopolymers, silicone, or the like.

In some of these examples, the gel acetonitrile as a solvent and a 1Mconcentration of a lithium salt, such as LiPF₆.

In some of these examples, the gel includes a dioxolane solvent and a 1Mconcentration of a Lithium salt, such as LiTFSI or LiPF₆.

In certain examples, the gel includes PVDF polymer, dioxolane solventand 1M concentration of LiFTSI or LiPF₆. In some other examples, the gelincludes PVDF polymer, acetonitrile (ACN) solvent and 1M concentrationof LiFTSI or LiPF₆. In some of these examples, the gel has a EC:PCsolvent and a 1M concentration of a lithium salt, such as LiTFSI orLiPF₆. In some of these examples, the composite and the gel show a lowimpedance of about 10 Ωcm².

In some examples, the gel is a composite electrolyte which includes apolymer and a ceramic composite with the polymer phase having a finitelithium conductivity. In some examples, the polymer is a single ionconductor (e.g., Li⁺). In other examples, the polymer is a multi-ionconductor (e.g., Li⁺ and electrons). The following non-limitingcombinations of polymers and ceramics may be included in the compositeelectrolyte. The composite electrolyte may be selected frompolyethyleneoxide (PEO) coformulated with LiCF₃SO₃ and Li₃N, PEO withLiAlO₂ and Li₃N, PEO with LiClO₄, PEO: LiBF₄—TiO₂, PEO with LiBF₄—ZrO₂.In some of these composites, in addition to the polymers, the compositeincludes an additive selected from Li₃N; Al₂O₃, LiAlO₃; SiO₂, SiC,(PO₄)³⁻, TiO₂; ZrO₂, or zeolites in small amounts. In some examples, theadditives can be present at from 0 to 95% w/w. In some examples, theadditives include Al₂O₃, SiO₂, Li₂O, Al₂O₃, TiO₂, P₂O₅,Li_(1.3)Ti_(1.7)Al_(0.3)(PO₄)₃, or (LTAP). In some of these compositeelectrolytes, the polymer present is polyvinylidenefluoride at about 10%w/w. In some of these as composite electrolytes, the composite includesan amount of a solvent and a lithium salt (e.g., LiPF₆). In some ofthese composites, the solvent is ethyl carbonate/dimethyl carbonate(EC/DMC) or any other solvent set forth herein. In some examples, thecomposite includes a solvent useful for dissolving lithium salts. Insome of the composite electrolytes set forth herein, the polymer servesseveral functions. In one instance, the polymer has the benefit ofameliorating interface impedance growth in the solid electrolyte even ifthe polymer phase conductivity is much lower than the ceramic. In otherinstances, the polymer reinforces the solid electrolyte mechanically. Insome examples, this mechanical reinforcement includes coformulating thesolid electrolyte with a compliant polymer such as poly paraphenyleneterephthalamide. These polymers can be one of a variety of forms,including a scaffold.

In some examples, set forth is an electrochemical stack including apositive electrode, wherein the positive electrode includes a gelcatholyte. In some examples, the gel catholyte includes a solventselected from the group consisting of ethylene carbonate (EC), propylenecarbonate (PC), dimethyl carbonate (DMC), methylene carbonate, andcombinations thereof; a polymer selected from the group consisting ofPVDF-HFP and PAN; and a salt selected from LiPF₆, LiBOB, or LFTSi.

In some examples, including any of the foregoing, the electrochemicalstack further includes a solid electrolyte and a bonding layer betweenthe positive electrode and the solid electrolyte. In some examples, thebonding layer is a phase inversion gel electrolyte, as described herein.In certain examples, the positive electrode includes a phase-inversiongel catholyte. In some examples, the phase inversion gel electrolyte isporous. In some examples, the phase inversion gel electrolyte is 10, 20,30, 40, 50, or 60% by volume porous.

In some examples, including any of the foregoing, set forth is apositive electrode which includes a phase inversion gel catholyte,wherein the phase inversion gel catholyte includes a solvent selectedfrom the group consisting of tetrahydrofuran (THF), ethylene carbonate(EC), propylene carbonate, dimethyl carbonate (DMC), methylenecarbonate, and combination thereof; a polymer selected from the groupconsisting of PVDF-HFP and PAN; and a non-solvent selected from toluene,acetone, and combination thereof and a salt selected from the groupconsisting of LiPF₆, LiBOB, and LFTSi.

In some examples, including any of the foregoing, set forth is a freestanding film of a gel or phase inversion gel electrolyte having aninterfacial impedance less than 10 Ωcm² at 60° C. when the film ispositioned between and directly in contact with an electrolyte separatorand a positive electrode.

In some examples, including any of the foregoing, set forth is a freestanding film which includes a phase inversion gel electrolyte, whereinthe gel electrolyte comprises a lithium salt, a polymer. Thephase-inversion gel is porous and the porosity can be tuned by, forexample, the solvent(s) in the gel and the rates at which the solvent(s)volatize away from the gel. In some examples, the polymer is selectedfrom the group consisting of polyacrylonitrile (PAN), polyvinylidenefluoride hexafluoropropylene (PVDF-HFP), or combination thereof. Incertain examples, the lithium salt is selected from LiPF₆, LiBOB, LiBF₄,LiClO₄, LiI, LiFSI, and LTFSI. In certain examples, the lithium salt isLiPF₆ at an average concentration of 0.5 M to 2M. In some examples, thelithium salt is LiTFSI at an average concentration of 0.5 M to 2M. Incertain examples, the lithium salt is present at a concentration from0.01 M to 10 M. In some examples, the solvent is selected from the groupconsisting of ethylene carbonate (EC), propylene carbonate, dimethylcarbonate (DMC), EMC, ethyl-methyl sulfone, dinitriles, sulfone,sulfolane, methylene carbonate, and combination thereof. In certainexamples, the solvent is a 1:1 w/w mixture of EC:PC. In certainexamples, the solvent is present at a residual amount, wherein theresidual amount of solvent is the amount remaining after the bondinglayer is dried. In certain examples, the residual amount is the minimumamount of solvent required to solvate the lithium salt. In certainexamples, the interfacial impedance is less than 10 Ωcm² at 60° C. whenthe film is positioned between and directly in contact with anelectrolyte separator and a positive electrode.

In some examples herein, set forth is a phase inversion bonding layer,wherein the phase inversion bonding layer has a porosity of at least10%.

In some examples herein, set forth is a phase inversion bonding layer,wherein the phase inversion bonding layer has a porosity of at least20%. In some examples herein, set forth is a phase inversion bondinglayer, wherein the phase inversion bonding layer has a porosity of atleast 30%. In some examples herein, set forth is a phase inversionbonding layer, wherein the phase inversion bonding layer has a porosityof at least 40%. In some examples herein, set forth is a phase inversionbonding layer, wherein the phase inversion bonding layer has a porosityof at least 50%. In some examples herein, set forth is a phase inversionbonding layer, wherein the phase inversion bonding layer has a porosityof at least 60%. In some examples herein, set forth is a phase inversionbonding layer, wherein the phase inversion bonding layer has a porosityof at least 70%.

V. Methods of Making Electrochemical Cells

In some examples, set forth herein is a method for making anelectrochemical device, including, providing a positive electrode,providing a free standing film of a gel electrolyte. In some examples agel electrolyte (referred to as a bonding agent) as set forth herein.

In some examples, the gel electrolyte includes a lithium salt, apolymer, and a solvent. In some examples, the polymer is selected fromthe group consisting of polyacrylonitrile (PAN), polypropylene,polyethylene oxide (PEO), polymethyl methacrylate (PMMA), polyvinylchloride (PVC), polyvinyl pyrrolidone (PVP), polyethylene oxidepoly(allyl glycidyl ether) PEO-AGE, polyethylene oxide2-methoxyethoxy)ethyl glycidyl ether (PEO-MEEGE), polyethylene oxide2-methoxyethoxy)ethyl glycidyl poly(allyl glycidyl ether)(PEO-MEEGE-AGE), polysiloxane, polyvinylidene fluoride (PVDF),polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), and rubbers suchas ethylene propylene (EPR), nitrile rubber (NPR),styrene-butadiene-rubber (SBR), polybutadiene polymer, polybutadienerubber (PB), polyisobutadiene rubber (PIB), polyisoprene rubber (PI),polychloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR),polyethyl acrylate (PEA), polyvinylidene fluoride (PVDF), orpolyethylene (e.g., low density linear polyethylene).

In certain examples, the polymer in the gel electrolyte ispolyacrylonitrile (PAN) or polyvinylidene fluoride hexafluoropropylene(PVDF-HFP). In certain examples, the polymer in the gel electrolyte isPAN, PVDF-HFP, PVDF-HFP and PAN, PMMA, PVC, PVP, PEO, or combinationsthereof. In certain examples, the lithium salt in the gel electrolyte isa lithium salt selected from LiPF₆, LiBOB, LiTFSi, LiBF₄, LiClO₄,LiAsF₆, LiFSI, LiAsF₆, LiClO₄, LiI, or LiBF₄.

In certain examples, the lithium salt in the gel electrolyte is alithium salt is selected from LiPF₆, LiBOB, and LFTSi.

In certain examples, the lithium salt in the gel electrolyte is LiPF₆ ata concentration of 0.5 M to 2M. In some examples, the concentration is0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8,1.9 or 2.0M.

In certain examples, the lithium salt in the gel electrolyte is LiTFSIat a concentration of 0.5 M to 2M. In some examples, the concentrationis 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8,1.9 or 2.0M.

In certain examples, the lithium salt in the gel electrolyte is presentat a concentration from 0.01 M to 10 M. In some examples, theconcentration is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1,1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5,2.6, 2.7, 2.8, 2.9, 3.0, 3.3, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9,2.0, 0.3, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 3.0, 3.1, 3.2, 3.3,3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7,5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1,7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.8, 8.4, 8.5,8.6, 8.7, 8.8, 8.9, 9.9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9,10.0 M.

In certain examples, the solvent is selected from ethylene carbonate(EC), diethylene carbonate, diethyl carbonate, dimethyl carbonate (DMC),ethyl-methyl carbonate (EMC), tetrahydrofuran (THF), γ-Butyrolactone(GBL), fluoroethylene carbonate (FEC), fluoromethyl ethylene carbonate(FMEC), trifluoroethyl methyl carbonate (F-EMC), fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-Tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE), fluorinated cyclic carbonate (F-AEC), propylene carbonate (PC),dioxolane, acetonitrile (ACN), succinonitrile, adiponitrile,hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, dimethyl sulfate, dimethyl sulfoxide (DMSO) ethyl-methylcarbonate, ethyl acetate, methyl butyrate, dimethyl ether (DME), diethylether, propylene carbonate, dioxolane, glutaronitrile, gammabutyl-lactone, toluene, or combinations thereof.

In certain examples, the solvent is a 1:1 w/w mixture of EC:PC.

In certain examples, the solvent is present as a residual amount. Insome examples, the residual amount is the amount of solvent remainingafter the bonding layer is dried. In some examples, the residual amountis the amount of solvent remaining after the bonding layer isspin-coated onto a substrate and dried. In some examples, the residualamount is the minimum amount of solvent required to solvate the lithiumsalt.

In yet other examples, the film lowers the interfacial impedance betweenan electrolyte separator and a positive electrode, when positionedbetween and directly in contact with an electrolyte separator and apositive electrode.

Incorporated herein are methods of making gel electrolytes, such asthose in U.S. Pat. No. 5,296,318, entitled RECHARGEABLE LITHIUMINTERCALATION BATTERY WITH HYBRID POLYMERIC ELECTROLYTE.

One Phase Gel Electrolyte

In some examples, set forth herein is a method of making a gelelectrolyte. This method, in some examples, includes the followingsteps.

In some examples, a solvent is provided and mixed with a polymer and alithium salt. In some examples, the solvent is volatilized toconcentrate the polymer and lithium salt.

In some examples, the solvent is selected from ethylene carbonate (EC),diethylene carbonate, diethyl carbonate, dimethyl carbonate (DMC),ethyl-methyl carbonate (EMC), tetrahydrofuran (THF), γ-Butyrolactone(GBL), fluoroethylene carbonate (FEC), fluoromethyl ethylene carbonate(FMEC), trifluoroethyl methyl carbonate (F-EMC), fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-Tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE), fluorinated cyclic carbonate (F-AEC), propylene carbonate (PC),dioxolane, acetonitrile (ACN), succinonitrile, adiponitrile,hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, dimethyl sulfate, dimethyl sulfoxide (DMSO) ethyl-methylcarbonate, ethyl acetate, methyl butyrate, dimethyl ether (DME), diethylether, propylene carbonate, dioxolane, glutaronitrile, gammabutyl-lactone, or combinations thereof.

In certain examples, the polymer is polyacrylonitrile (PAN) orpolyvinylidene fluoride hexafluoropropylene (PVDF-HFP). In certainexamples, the polymer in the gel electrolyte is PAN, PVDF-HFP, PVDF-HFPand PAN, PMMA, PVC, PVP, PEO, or combinations thereof. In certainexamples, the lithium salt in the gel electrolyte is a lithium salt isselected from LiPF₆, LiBOB, LiTFSi, LiBF₄, LiClO₄, LiAsF₆, LiFSI,LiAsF₆, LiClO₄, LiI, or LiBF₄. In certain examples, several lithiumsalts may be present simultaneously in different concentrations.

Phase Inversion Gel Electrolyte

In some examples, set forth herein is a method of making a phaseinversion gel. This method, in some examples, includes the followingsteps.

In some examples, a polymer is dissolved in a solvent which dissolvesthe polymer. For example, when the polymer is PVDF-HFP, the solvent maybe tetrahydrofuran (THF). In some examples, the ratio of PVDF-HFP:THF isbetween 0.01 and 10. In some examples, the ratio of PVDF-HFP:THF is0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3,0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In someexamples, the polymer and solvent are mixed to form a mixture. In someexamples, this mixture is heated. In certain examples, the mixture isheated to volatilize the solvent. In some examples, the mixture isstirred. In some examples, the stirring is at 100 revolutions per minute(RPM). In certain examples, a non-solvent is then added. In some ofthese examples, the non-solvent is toluene when the polymer is PVDF-HFP.In some examples, non-solvent is added to that the weight of thenon-solvent with respect to the weight of the PVDF-HFP is 1, 2, 3, 4, 5,6, 7, 8, 9, or 10 times. For example, the (weight of thenon-solvent)/(weight of the polymer) is 1, 2, 3, 4, 5, 6, 7, 8, 9, or10. In some examples, the mixture with the non-solvent is heated untilthe solvent evaporates or is reduced to a residual amount. In someexamples, the heated mixture is spin-cast onto a substrate to form afilm. In some examples, the rate of spin for the spin-coater determinesthe thickness of the spin-cast film. In some examples, the spin-castfilm can be released from the substrate on which it was cast to form afree standing film.

EXAMPLES Example 1—Making an Electrochemical Stack Having a BondingLayer

In this example, a free standing gel electrolyte film was firstprepared.

A blend of ethylene carbonate (EC) and propylene carbonate (PC) solventswas prepared in a 1:1 w/w ratio. The lithium salt lithiumhexafluorophosphate was added to this mixture to achieve a 1M solution.To form the gel solution, 0.8 grams of a PVDF-HFP polymer (Kynar 2801)was mixed 2.8 grams of the lithium hexafluorophosphate solution and 8.5grams of a solvent, THF (Tetrahydrofuran). The solution was cast viadoctor blade onto a glass substrate inside a glove box. The film wasallowed to dry in the glove box for 4 hours. The dry film thickness was45 μm. This dry film was used as the gel electrolyte 103 below.

As shown in FIG. 1 , two electrochemical stacks were prepared. Thelayers were pressed together in the actual electrochemical stack, but inFIG. 1 the layers are separated for illustrative purposes.

In one example, 100, the electrochemical stack, 100, included a positiveelectrode, 102, having a Ni—Co—Al positive electrode active material,with C65 carbon and a gel catholyte. The gel catholyte included an 80:20w/w mixture of PVDF-HFP in EC:PC with 1M LiPF₆. This stack also includeda solid lithium-stuffed garnet, 104, Li₇La₃Zr₂O₁₂ 0.35 Al₂O₃, 50 μmthick electrolyte separator. Laminated to the bottom of, 104, waslithium metal, 105.

In another example, 101, the electrochemical stack, 101, includes apositive electrode, 102, having an Ni—Co—Al positive electrode activematerial, with C65 carbon and a gel catholyte. The gel catholyteincluded an 80:20 w/w mixture of PVDF-HFP in EC:PC with 1M LiPF₆. Thisstack also included a solid lithium-stuffed garnet, 104,Li₇La₃Zr₂O₁₂Al₂O₃, 50 μm thick electrolyte separator. Evaporated to thebottom of, 104, was lithium metal, 105. Positioned in between and indirect contact with layers, 102 and 104, was a gel electrolyte, 103. Gelelectrolyte/bonding layer, 103, was prepared as noted above.

The combination of a gel and a solid lithium-stuffed garnet wassurprisingly stable. Organic solvents typically react with garnet.However, the gel used in this example did not. Typically carbonatesreact to produce CO₂ at high V or high T, and CO₂ may react with garnet.This results in an increase in impedance due to the resistive layerformed by the reaction of CO₂ and garnet. This effect is exacerbated athigher voltages. For this reason, it is not typical to combine carbonateelectrolytes with a garnet. However, the gel used in this example didnot appreciably react with garnet as demonstrated by the low impedanceobserved, even when cycled to high voltages. This was a surprisingeffect since one might have expected that the organic solvent in the gelwould have reacted with the solid lithium-stuffed garnet just as anorganic solvent, absent a gel, would have been expected to react. Thelack of a reaction between the gel and the lithium-stuffed garnet waspossibly due to the slow diffusion of the solvent and salts in the gel.Without being bound by any particular theory, it is also possible thatthe gel layer inhibits diffusion of CO₂ to the garnet interface. If thebonding layer is an electronic insulator, it protects the separatorelectrolyte from the voltage of the cathode and any undesirableside-reactions that may result due to the high voltage instability ofthe separator. As a separator used in a lithium metal anode battery mustbe stable to lithium, there are few candidate separator materials thatare simultaneously stable to the high voltage of the positive electrodeand the low voltage of the negative electrode. The gel layer may thusenable a larger set of separator materials.

Example 2—Testing an Electrochemical Stack Having a Bonding Layer

Both stacks, 100 and 101, from Example 1 were analyzed to see theirvoltage response as a function of time for a pulsed currentelectrochemical test. An OCV step was applied until time approximately2000 s in the graph, then a current was applied of 0.1 mA/cm² untilabout time 5600 s, when the OCV was monitored under no applied current.The voltage response to the current step is monitored and shown in FIG.2 . The electrochemical stack, 100, was observed to have an immediaterise in impedance. This indicates too high of an interfacial ASR betweenthe layers in the electrochemical stack. This Example demonstrates thatpressing a cathode onto a garnet surface is ineffective and results in avery large impedance. However, when a gel electrolyte is used, andplaced between and in direct contact with solid electrolyte and thepositive electrode, the interfacial impedance is reduced.

FIG. 3 shows a GITT test of pulsed current throughout a full charge anddischarge cycle for one cell with a bonding layer when cycled between2.7-4.2V. Full capacity can be obtained from the cell with a relativelylow resistance.

Example 3—Making a Spin Coated Gel Bonding Layer

A blend of ethylene carbonate (EC) and propylene carbonate (PC) solventswas prepared in a 1:1 w/w ratio. The lithium salt, LiPF₆, was added tothis mixture to achieve a 1M solution. PAN polymer was mixed with thesolution in a measured volume ratio PAN to EC:PC. The solution wasspin-cast using a Laurel Technologies, Spincoater for up to 60 secondsto form a film. By varying the spin-cast RPM(s), thicker or thinner freestanding films were prepared. The film was allowed to dry at roomtemperature on a garnet substrate for twenty-four hours. FIG. 4 showsthe thickness of a PAN-containing film, which is as a function of thespin-cast RPM. The scale bar in FIG. 4 is 5 μm. Higher RPM results inthinner films. FIG. 5 shows a 47.4% PAN gel electrolyte which wasspin-cast at 2000 RPM. The gel electrolyte, 501, is positioned on top ofthe garnet separator, 502. The scale bar in FIG. 5 is 100 μm.

Example 4—Testing Individual Electrochemical Layers with Spin Coated GelBonding Layer

Determination of the interfacial resistance between a bonding layer anda garnet electrolyte requires measurement of a full cell resistance andsubtraction of all other resistance components. The followingexperiments are used to determine the resistance of each layer andinterface in a full cell so as to enable calculation of the interfacialresistance between a gel and a garnet separator (ASR_(B-G)). As shown inFIG. 6 , an electrochemical stack was provided having Li metal 603, asolid lithium-stuffed garnet, 602, Li₇La₃Zr₂O₁₂Al₂O₃, 50 μm thick film,and a lithium metal electrode, 601. This configuration is referred to asymmetric cell Li|garnet|Li cell.

FIG. 7 shows a stack consisting of Li|Garnet|scGel|fsGel|Li-foil whichwas constructed and measured. Here, scGel refers to the spin-coatprepared gel electrolyte layer, 705 and fsGel refers to the doctor-bladecoated free standing gel electrolyte layer, 702. Based on theaforementioned results, the ASR in a stackLi|Garnet|scGel|fsGel|Li-foil=ASR_(tot) was measured.

By determining, the contributions from all other components in thestructure Li|Garnet|scGel|fsGel|Li-foil (FIGS. 6 and 7 ), the resistanceof the scGel|Garnet interface was calculated according toASR_(I/F,SSE-scGel)=ASR_(tot)−ASR_(fsGel,bulk)−ASR_(SSE,bulk)-ASR_(fsGel-Li)-ASR_(I/F SSE-Li).In FIG. 7 , layer 701 is a Li-foil. Layer 703 is the solid electrolyteseparator made of Li₇La₃Zr₂O₁₂0.35Al₂O₃. Layer 704 is Li metal. Thiscalculation assumes that the fsGel-scGel ASR is negligible. The ASR ofthe garnet bulk was found to be 10 Ωcm², the ASR of the garnet-Liinterface was 3±2 Ωcm².

In total, three gel electrolytes were prepared with the followingcompositions: (A) 30% w/w PVDF-HFP in EC:PC; (B) 50% w/w PVDF-HFP inEC:PC; and (C) 18.4% w/w PAN in EC:PC.

The associated ASR of the films at 60° C. is shown as a function ofspin-coating RPM in FIG. 8 . In the case B. PVDF-HFP (50%) where thespin speed was 1,500 RPM and the spin coated gel thickness was 5.5 μmthick the total ASR for the Li-garnet-gel was 65±12 Ωcm². The ASR of thegarnet-gel interface was found to be as low as 22 Ωcm² at 60° C. in thisconfiguration. In full cells, the ASR of the garnet-gel interface wasfound to be between 1 and 5 Ωcm² at 45° C. This ASR is surprisingly lowcompared to the cells from Example 1, where a cell with no bonding layerwas too resistive to be charged. It is surprising due to the fact thatan additional resistive layer may be introduced into the cell and thetotal cell resistance decreases.

Example 5—Comparing Gel Bonding Layers with Other Materials

A garnet pellet is used to separate two isolated chambers full of liquidelectrolyte of EC:PC (1M LiPF₆). A Li foil is held in each chamber and acurrent is passed which causes dissolution of lithium on one electrodeand plating of lithium on the other electrode. To pass current, lithiumions must travel through the liquid in the first chamber, pass throughthe garnet pellet, and finally through the liquid in the other chamberto reach the lithium foil. The voltage drop across the entire cell ismeasured throughout this process. The impedance of the liquid-garnetinterface and be deduced by knowledge of the other sources of voltagedrop in the system including the liquid impedance itself and theimpedance of the pellet. It was found that the impedance of theGarnet-Liquid electrolyte (labeled “Liquid” in FIG. 9 ) interface was onthe order of 5,000 Ωcm². These results show that a liquid reacts withthe Li metal anode and results in a high ASR. The liquid was observed toreact with Li metal to form a high impedance layer, such as a lithiumcarbonate layer.

The garnet was also paired with a solid (a lithium-phosphorus-sulfideelectrolyte) or polymer bonding layer (PEO with LiClO₄) in anelectrochemical stack with the same configuration as FIG. 7 . The garnetoxide interfacial impedance was also rather high, e.g., 60-202 Ωcm² at60° C., as shown in FIG. 9 , to the detriment of any device whichincludes this pair. These results show that gels, as compared toliquids, solids, or polymers pair with garnet electrolyte separators toprotect the Li metal negative electrode and provide a low ASR interface.

Gel electrolytes usually have a lower ionic conductivity than a liquidelectrolyte. Thus, by pairing a gel electrolyte with a garnet, asopposed to a liquid electrolyte, one would expect that the total ASRwould be higher for the gel-electrolyte-garnet as compared to theliquid-electrolyte-garnet. However, the results herein demonstratesurprisingly that the gel-electrolyte-garnet has lower ASR, than thecorresponding liquid-electrolyte-garnet.

As shown in FIG. 9 , the gel electrolyte resulted in a surprisinglylower interfacial ASR than either of the liquid, polymer, or solidelectrolytes. One interpretation of the surprisingly lower interfacialASR of a gel as compared to a liquid is that a gel enforces wetting ofthe interface, whereas many liquids do not easily wet the separatorinterface. A wettability measurement is shown in FIG. 14 , showing alarge contact angle between the separator and electrolyte.

Example 6—Making a Phase Inversion Gel Bonding Layer

PVDF-HFP polymer was dissolved in Tetrahydrofuran (THF) in a ratio ofPVDF-HFP:THF=0.05:1 heated on a hot-plate to 80° C. and stirred at 100rpm till the polymer dissolves. Then the non-solvent toluene was addeddrop-wise to the solution in a ratio of such that the weight of tolueneadded is 3.5 times PVDF-HFP. The solution was spin-cast using aspin-coater from Laurel Technologies up to 60 seconds. The spin-coaterRPM can be adjusted to obtain gel films of different thicknesses. HigherRPM results in thinner films. FIG. 10 shows the plan view and FIG. 11shows a cross-section of the phase-inversion gel (thickness 1 micron)spin coated on Si wafer, at a speed of 1200 rpm. In FIG. 10 , the porousspace is shown in black and labeled as 1001. The polymer matrix (i.e.,network) is shown in gray and labeled as 1002. The full-cell stackcross-section is as shown in FIG. 11 . In FIG. 11 , the phase-inversiongel electrolyte is labeled as 1101 and is positioned on top of a siliconsubstrate. The silicon substrate is labeled as 1102.

Example 7—Testing the Individual Electrochemical Layer after PhaseInversion Gel Bonding

The conductivity of the gel was evaluated by creating a “sandwich” of athick, free standing version of the gel (100 microns thick) soaked inelectrolyte EC:EMC with 1M LiPF₆, in between two stainless steel spacersand assembling this sandwich in a coin cell. At 45° C., the resistanceof this stack is 2-2.5Ω, amounting to a total ASR of 4 Ω·cm². The bulkresistance of a 1 micron thick gel is expected to be 100 times less,accounting for a small impedance contribution in a full stack.

Example 8—Testing the Bonding Layer after Phase Inversion Gel Bonding ina Stack

The spin-coated gel on garnet was assembled against another spin-coatedgel on garnet to create a sandwich with two spin coated gels in betweentwo garnet pellets. The pellets are coated with 2 or 30 μm evaporatedlithium on the other side. This stack was assembled in a coin cell stacksuch that the gel is under the same pressure as it would be under a fullcell stack. Electrochemical Impedance Spectroscopy response of thisstack is shown in FIG. 13 .

There were two parallel resistive-capacitative (RC) responses observedin this system: the first corresponds to bulk impedance of the twogarnet pellets, marked by R1 in FIG. 13 . The second semi-circlecorresponds to the resistive capacitative (RC) response of twogarnet-gel interfaces. The impedance corresponding to the x-intercept ofthese semi-circles was interpreted as R_(bulk,garnet) andR_(garnet-gel interface) respectively. The area specific resistance ofthe interface was determined by dividing R2 by two (since there are twointerfaces) and multiplying with the electrode area (0.636 cm²). Theinterfacial impedance between gel and garnet was found to be less than 2Ωcm² at 45° C. and less than 5 Ωcm² at 20° C.

The foregoing description of the embodiments of the disclosure has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the claims to the precise forms disclosed.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in light of the abovedisclosure.

The language used in the specification has been principally selected forreadability and instructional purposes, and it may not have beenselected to delineate or circumscribe the inventive subject matter. Itis therefore intended that the scope of the disclosure be limited not bythis detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure, which is set forth in the following claims.

What is claimed is:
 1. An electrochemical stack, comprising: a lithiummetal (Li) negative electrode, a positive electrode, an electrolyteseparator film comprising a lithium-stuffed garnet, and a bonding layer;wherein the bonding layer comprises a lithium salt, a polymer, and asolvent; wherein the polymer in the bonding layer is selected frompolyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidenefluoride hexafluoropropylene (PVDF-HFP), polymethyl methacrylate (PMMA),polyvinyl chloride (PVC), polyvinyl pyrrolidone (PVP), polyethyleneoxide (PEO), polyethylene oxide poly(allyl glycidyl ether) (PEO-AGE),polyethylene oxide 2-(methoxyethoxy)ethyl glycidyl ether (PEO-MEEGE),polyethylene oxide 2-(methoxyethoxy)ethyl glycidyl poly(allyl glycidylether) (PEO-MEEGE-AGE), polyethylene carbonate, polyphenylene sulfide,polypropylene carbonate, and combinations thereof; and wherein thebonding layer is characterized by a thickness about 1 nm to about 5 μm;wherein the electrolyte separator film is characterized by a thicknessof 0.1 μm to about 50 μm; wherein the electrolyte separator has adensity greater than 95% of its theoretical density as determined byscanning electron microscopy; wherein the electrolyte separator film isin direct contact with the Li metal negative electrode; and wherein thebonding layer directly contacts, and is positioned between, theelectrolyte separator film and the positive electrode; wherein theelectrolyte separator has a surface directly contacting the lithiummetal negative electrode, wherein the surface only includes materialwhich is the same as the material in a bulk of the electrolyteseparator.
 2. The electrochemical stack of claim 1, wherein theelectrolyte separator film is characterized by a thickness of 10 μm to50 μm.
 3. The electrochemical stack of claim 1, wherein the Li negativeelectrode comprises a layer of Li metal having a thickness from 1 nm to30 μm in the fully discharged state.
 4. The electrochemical stack ofclaim 1, wherein the Li metal negative electrode comprises a layer of Limetal having a thickness from 1 μm to 50 μm in the fully charged state.5. The electrochemical stack of claim 1, wherein the electrolyteseparator film has a surface flatness of 0.1 μm to about 50 μm.
 6. Theelectrochemical stack of claim 1, wherein the polymer in the bondinglayer is selected from PAN, PVDF, PMMA, PVC, PVP, PEO, polyethylenecarbonate, polyphenylene sulfide, polypropylene carbonate, and acombination thereof.
 7. The electrochemical stack of claim 1, whereinthe polymer in the bonding layer is selected from polyvinylidenefluoride (PVDF), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP),and combinations thereof.
 8. The electrochemical stack of claim 1,wherein the electrolyte separator is nearly 100% dense electrolyte andhas a planar surface.
 9. The electrochemical stack of claim 1, whereinthe lithium salt in the bonding layer is selected from the groupconsisting of LiPF₆, LiBOB, LiBETI, LiTFSI, LiBF₄, LiClO₄, LiAsF₆,LiFSI, LiI, LiBF₄, and a combination thereof.
 10. The electrochemicalstack of claim 1, wherein the solvent in the bonding layer is selectedfrom the group consisting of ethylene carbonate (EC), diethylenecarbonate or diethyl carbonate (DC), dimethyl carbonate (DMC),ethyl-methyl carbonate (EMC), tetrahydrofuran (THF), γ-Butyrolactone(GBL), fluoroethylene carbonate (FEC), fluoromethyl ethylene carbonate(FMEC), trifluoroethyl methyl carbonate (F-EMC), fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane(F-EPE),fluorinated cyclic carbonate (F-AEC), propylene carbonate (PC),dioxolane, acetonitrile (ACN), succinonitrile, adiponitrile,hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, dimethyl sulfate, prop-1-ene-1,3-sultone (PES), dimethylsulfoxide (DMSO), ethyl-methyl carbonate, ethyl acetate, methylbutyrate, dimethyl ether (DME), diethyl ether, propylene carbonate,dioxolane, glutaronitrile, gamma butyl-lactone, and combinationsthereof.
 11. The electrochemical stack of claim 10, wherein the amountof solvent in the bonding layer is the minimum amount of solventrequired to solvate the lithium salt.
 12. The electrochemical stack ofclaim 1, wherein the interfacial impedance between the electrolyteseparator film and the positive electrode is less than 50 Ω·cm² at 50°C.
 13. The electrochemical stack of claim 1, wherein the positiveelectrode further comprises a catholyte.
 14. The electrochemical stackof claim 13, wherein the catholyte is a gel electrolyte; wherein thepositive electrode comprises a gel catholyte which has the samecomposition as the bonding layer.
 15. The electrochemical stack of claim14, wherein the positive electrode comprises a gel catholyte comprising:a solvent selected from the group consisting of ethylene carbonate (EC),propylene carbonate (PC), dimethyl carbonate (DMC), methylene carbonate,and combinations thereof; a polymer selected from the group consistingof PVDF, PVDF-HFP, PAN, and combinations thereof; and a salt selectedfrom the group consisting of LiPF₆, LiBOB, and LiTFSI.
 16. Theelectrochemical stack of claim 1, wherein the bonding layer does notcomprise components which volatilize and diffuse around the electrolyteseparator film to contact the Li metal negative electrode.
 17. Theelectrochemical stack of claim 1, wherein the polymer is PVDF.
 18. Theelectrochemical stack of claim 1, wherein the polymer is PVDF-HFP andPAN.